A117062 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

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

(list; graph; refs; listen; history; text; internal format)

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