A358932 a(n) is the smallest centered n-gonal number with binary weight n.

19, 85, 31, 469, 253, 2025, 5995, 4061, 15742, 48061, 8191, 220543, 384766, 3080161, 3272671, 6192631, 8385271, 31453021, 58159102, 249495467, 401469279, 268418041, 134193151, 2885548927, 1610563582, 8589393821, 33280753395, 83751780091, 171658174447

Offset: 3

Author

Ilya Gutkovskiy, Dec 06 2022

Keywords

• nonn
• base

Examples

			31 is the smallest centered pentagonal number with binary weight 5 (31_10 = 11111_2), so a(5) = 31.
		

Links

• Eric Weisstein's World of Mathematics, Centered Polygonal Number
• Index entries for sequences related to binary expansion of n

Crossrefs

Cf. A000120, A358930, A358931.

Programs

Mathematica

c[n_, k_] := n*k*(k + 1)/2 + 1; a[n_] := Module[{k = 1, ck}, While[DigitCount[ck = c[n, k], 2, 1] != n, k++]; ck]; Array[a, 25, 3] (* Amiram Eldar, Dec 09 2022 *)