Nonagonal number
Encyclopedia
A nonagonal number or enneagonal number is a polygonal number
that represents a nonagon. The nonagonal number for n is given by the formula:
The first few nonagonal numbers are:
The parity of nonagonal numbers follows the pattern odd-odd-even-even.
Letting N(n) give the nth nonagonal number and T(n) the nth triangular number,
Polygonal number
In mathematics, a polygonal number is a number represented as dots or pebbles arranged in the shape of a regular polygon. The dots were thought of as alphas . These are one type of 2-dimensional figurate numbers.- Definition and examples :...
that represents a nonagon. The nonagonal number for n is given by the formula:
The first few nonagonal numbers are:
- 1, 9, 2424 (number)24 is the natural number following 23 and preceding 25.The SI prefix for 1024 is yotta , and for 10−24 yocto...
, 4646 (number)46 is the natural number following 45 and preceding 47.- In mathematics :Forty-six is a Wedderburn-Etherington number, an enneagonal number and a centered triangular number. It is the sum of the totient function for the first twelve integers. 46 is the largest even integer that can't be expressed...
, 7575 (number)75 is the natural number following 74 and preceding 76.-In mathematics:As the sum of the first five pentagonal numbers, seventy-five is a pentagonal pyramidal number. It is also an enneagonal number....
, 111111 (number)111 is the natural number following 110 and preceding 112. It is the lowest positive integer requiring six syllables to name in American English, or seven syllables in Canadian and British English...
, 154154 (number)One hundred and fifty-four is the natural number following one hundred and fifty-three and preceding one hundred and fifty-five.-In mathematics:* 154 is a nonagonal number...
, 204204 (number)204 is the natural number following 203 and preceding 205. It may be written as "two hundred four" or "two hundred and four".-In mathematics:...
, 261, 325, 396, 474, 559, 651, 750, 856, 969, 10891089 (number)1089 is the integer after 1088 and before 1090.It is a square number , a nonagonal number, a 32-gonal number, a 364-gonal number, and a centered octagonal number.In base 10, the following steps always yield 1089:...
, 1216, 1350, 1491, 1639, 1794, 1956, 2125, 2301, 2484, 2674, 2871, 3075, 3286, 3504, 3729, 3961, 4200, 4446, 4699, 4959, 5226, 5500, 5781, 6069, 6364, 6666, 6975, 7291, 7614, 7944, 8281, 8625, 8976, 9334, 9699.
The parity of nonagonal numbers follows the pattern odd-odd-even-even.
Letting N(n) give the nth nonagonal number and T(n) the nth triangular number,