A359093 a(n) is the index of the smallest n-gonal number whose sum of digits is n.

2, 2, 2, 2, 2, 2, 2, 10, 11, 6, 7, 11, 11, 4, 11, 9, 10, 29, 24, 29, 29, 29, 29, 29, 36, 28, 83, 69, 79, 110, 56, 83, 110, 72, 164, 236, 119, 178, 299, 209, 218, 308, 216, 416, 596, 506, 277, 443, 579, 589, 1172, 1217, 991, 1676, 1779, 2315, 1325, 1659, 3125, 2576

Offset

3,1

Links

Harvey P. Dale, Table of n, a(n) for n = 3..100

Eric Weisstein's World of Mathematics, Polygonal Number

Mathematica

p[n_, k_] := (n - 2)*k*(k - 1)/2 + k; a[n_] := Module[{k = 1}, While[Plus @@ IntegerDigits[p[n, k]] != n, k++]; k]; Array[a, 60, 3] (* Amiram Eldar, Dec 16 2022 *)
Table[Module[{k=1}, While[Total[IntegerDigits[PolygonalNumber[n, k]]]!=n, k++]; k], {n, 3, 70}] (* Harvey P. Dale, Dec 27 2024 *)

Crossrefs

Cf. A007953, A359003.

Sequence in context: A248771 A339446 A339166 * A291721 A109913 A197169

Adjacent sequences: A359090 A359091 A359092 * A359094 A359095 A359096

Keyword

nonn,base

Author

Ilya Gutkovskiy, Dec 16 2022

Status

approved