OFFSET
1,1
EXAMPLE
a(1) = 12 as witnessed by 11 = 1 + 10 and 13 = 3 + 10;
a(5) = 462 as witnessed by 461 = 55 + 406 and 463 = 28 + 435.
MATHEMATICA
s = Select[Union@ Flatten@ Table[i(i + 1)/2 + j(j + 1)/2, {i, 200}, {j, 0, i}], PrimeQ@ # &]; t = Select[Range@ Length@s - 1, s[[ # ]] + 2 == s[[ # + 1]] &]; s[[t]] + 1 (* Robert G. Wilson v, Apr 27 2006 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Greg Huber, Apr 24 2006
EXTENSIONS
More terms from Robert G. Wilson v, Apr 27 2006
STATUS
approved