Triangle of coefficients in expansion of (1+13x)^n.

Terms

a(0) =1a(1) =1a(2) =13a(3) =1a(4) =26a(5) =169a(6) =1a(7) =39a(8) =507a(9) =2197a(10) =1a(11) =52a(12) =1014a(13) =8788a(14) =28561a(15) =1a(16) =65a(17) =1690a(18) =21970a(19) =142805a(20) =371293a(21) =1a(22) =78a(23) =2535a(24) =43940a(25) =428415a(26) =2227758a(27) =4826809a(28) =1a(29) =91