This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A253384 #10 Jan 22 2015 07:05:23 %S A253384 1,-5,2,-5,-34,3,-5,290,-105,4,-5,-1870,2055,-236,5,-5,10280,-30345, %T A253384 7864,-445,6,-5,-50956,377895,-196256,22235,-750,7,-5,234812,-4194393, %U A253384 4090264,-824485,52170,-1169,8,-5,-1024900,42834855,-75271592,25302875,-2669430,107695,-1720,9 %N A253384 Triangle read by rows: T(n,k) appears in the transformation Sum_{k=0..n} (k+1)*x^k = Sum_{k=0..n} T(n,k)*(x+3k)^k. %C A253384 Consider the transformation 1 + 2x + 3x^2 + 4x^3 + ... + (n+1)*x^n = T(n,0)*(x+0)^0 + T(n,1)*(x+3)^1 + T(n,2)*(x+6)^2 + ... + T(n,n)*(x+3n)^n, for n >= 0. %F A253384 T(n,n) = n + 1, n >= 0. %F A253384 T(n,n-1) = n - 3*n^2 - 3*n^3, for n >= 1. %F A253384 T(n,n-2) = (n-1)*(9*n^4 - 9*n^3 - 24*n^2 + 6*n + 2)/2, for n >= 2. %F A253384 T(n,n-3) = (2-n)*(9*n^6 - 54*n^5 + 63*n^4 + 99*n^3 - 138*n^2 + 9*n + 10)/2, for n >= 3. %e A253384 The triangle T(n,k) starts: %e A253384 n\k 0 1 2 3 4 5 6 7 ... %e A253384 0: 1 %e A253384 1: -5 2 %e A253384 2: -5 -34 3 %e A253384 3: -5 290 -105 4 %e A253384 4: -5 -1870 2055 -236 5 %e A253384 5: -5 10280 -30345 7864 -445 6 %e A253384 6: -5 -50956 377895 -196256 22235 -750 7 %e A253384 7: -5 234812 -4194393 4090264 -824485 52170 -1169 8 %e A253384 ... %e A253384 ----------------------------------------------------------------- %e A253384 n = 3: 1 + 2*x + 3*x^2 + 4*x^3 = -5*(x+0)^0 + 290*(x+3)^1 - 105*(x+6)^2 + 4*(x+9)^3. %o A253384 (PARI) T(n, k)=(k+1)-sum(i=k+1, n, (3*i)^(i-k)*binomial(i, k)*T(n, i)) %o A253384 for(n=0, 10, for(k=0, n, print1(T(n, k), ", "))) %Y A253384 Cf. A247236, A247237, A253381, A253382. %K A253384 sign,tabl %O A253384 0,2 %A A253384 _Derek Orr_, Dec 31 2014 %E A253384 Edited; name changed, cross references added. - _Wolfdieter Lang_, Jan 22 2015