OFFSET
0,1
FORMULA
a(n) <= n^2 + n + 2. For n>0, a(n) <= n^n + n + 1.
EXAMPLE
Least prime p such that triangular(3)*p is a triangular number is p=11, so a(3) = 11.
CROSSREFS
KEYWORD
nonn
AUTHOR
Alex Ratushnyak, May 16 2013
STATUS
approved