A279846 Numbers that are centered k-gonal numbers for three or more values of k.

1, 31, 37, 43, 46, 61, 67, 73, 79, 85, 91, 106, 109, 121, 127, 133, 136, 145, 151, 157, 166, 169, 181, 199, 211, 217, 226, 232, 235, 241, 253, 265, 271, 274, 277, 289, 295, 301, 307, 313, 316, 325, 331, 337, 343, 361, 379, 391, 397, 406, 409, 421, 433, 451, 463, 469, 481, 496, 505, 511

Offset

1,2

Comments

Numbers satisfying 1 + n*m*(m+1)/2 for three or more values of (n,m), where n >= 0 m > 1.

Numbers in this sequence appear in A101321 at least four times (because the second column contains every positive integer).

Links

Daniel Sterman, Table of n, a(n) for a(n)<1000

Example

109 is in the sequence because 109 is a centered triangular number, a centered 18-gonal number, and a centered 36-gonal number.

Crossrefs

Cf. A062712 (rough equivalent for polygonal numbers).

Cf. A101321 (table of all centered polygonal numbers).

Cf. A275340 (list of nontrivial centered polygonal numbers).

Sequence in context: A051267 A073521 A180540 * A291994 A255223 A230225

Adjacent sequences: A279843 A279844 A279845 * A279847 A279848 A279849

Keyword

nonn

Author

Daniel Sterman, Dec 20 2016

Status

approved