1,2

a(4) = 15 = sum of row 4, triangle A131411; (3 + 3 + 4 + 5).

Cf. A131411.

Sequence in context: A003452 A000148 A095091 this_sequence A052130 A065506 A121165

Adjacent sequences: A131409 A131410 A131411 this_sequence A131413 A131414 A131415

nonn

Gary W. Adamson (qntmpktK(AT)yahoo.com), Jul 08 2007