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

Author

Daniel Sterman, Dec 20 2016

Keywords

• nonn

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).

Examples

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

Links

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

Crossrefs

Cf. A062712 (rough equivalent for polygonal numbers).

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

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