OFFSET
0,3
LINKS
Harvey P. Dale, Table of n, a(n) for n = 0..1000
EXAMPLE
105 is in the sequence because (1) it is a triangular number and (2) the sum of its digits 1+0+5=6 is a hexagonal number.
MATHEMATICA
Join[{0}, Select[Accumulate[Range[350]], IntegerQ[(1+Sqrt[8Total[ IntegerDigits[#]]+1])/4]&]] (* Harvey P. Dale, Jun 06 2011 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Luc Stevens (lms022(AT)yahoo.com), Apr 26 2006
EXTENSIONS
Corrected and extended by Harvey P. Dale, Jun 06 2011
STATUS
approved