0,2

a(4) = 21 = sum of row 4 terms of A131402: (1 + 6 + 7 + 6 + 1).

Cf. A131402.

Sequence in context: A066819 A114279 A101400 this_sequence A052540 A018106 A079342

Adjacent sequences: A131400 A131401 A131402 this_sequence A131404 A131405 A131406

nonn

Gary W. Adamson (qntmpkt(AT)yahoo.com), Jul 07 2007