OFFSET
1,3
EXAMPLE
66 is in the sequence because (1) it is a triangular number and (2) the sum of its digits 6+6=12 is a pentagonal number.
PROG
(PARI) isok(n) = ispolygonal(n, 3) && ispolygonal(sumdigits(n), 5); \\ Michel Marcus, Feb 26 2014
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Luc Stevens (lms022(AT)yahoo.com), Apr 26 2006
STATUS
approved