A117062 Hexagonal numbers for which the sum of the digits is also a hexagonal number.

0, 1, 6, 15, 231, 276, 780, 861, 1653, 1770, 2850, 3003, 4371, 4560, 5995, 6216, 6441, 11175, 14028, 17205, 17578, 20301, 20706, 24090, 24531, 24976, 28203, 32640, 33153, 36856, 37401, 43071, 47278, 52975, 54946, 56953, 67528, 69751, 76636

Offset

0,3

Links

Harvey P. Dale, Table of n, a(n) for n = 0..1000

Example

1770 is in the sequence because (1) it is a hexagonal number and (2)the sum of its digits 1+7+7+0=15 is also a hexagonal number.

Mathematica

Module[{nn=400, hn}, hn=PolygonalNumber[6, Range[0, nn]]; Select[hn, MemberQ[ hn, Total[ IntegerDigits[#]]]&]] (* Harvey P. Dale, Apr 14 2022 *)

Prog

(PARI) isok(n) = ispolygonal(n, 6) && ispolygonal(sumdigits(n), 6); \\ Michel Marcus, Feb 26 2014

Crossrefs

Cf. A000384.

Sequence in context: A013224 A013230 A306342 * A003155 A335578 A199095

Adjacent sequences: A117059 A117060 A117061 * A117063 A117064 A117065

Keyword

base,nonn

Author

Luc Stevens (lms022(AT)yahoo.com), Apr 16 2006

Status

approved