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 A209634 #19 Sep 29 2013 07:17:29 %S A209634 1,4,7,1,10,4,13,7,1,16,10,4,19,13,7,1,22,16,10,4,25,19,13,7,1,28,22, %T A209634 16,10,4,31,25,19,13,7,1,34,28,22,16,10,4,37,31,25,19,13,7,1,40,34,28, %U A209634 22,16,10,4,43,37,31,25,19,13,7,1,46,40,34,28,22,16,10 %N A209634 Triangle with (1,4,7,10,13,16...,(3*n-2),...) in every column, shifted down twice. %C A209634 OEIS contains a lot of similar sequences, for example A152204, A122196, A173284. %C A209634 Row sums for this sequence gives A006578. %C A209634 In general, by given triangle with (A-B,2*A-B,...,A*n-B,...) in every column, shifted down K-times, we have the row sum s(n)= A*(n*n+K*n+nmodK)/(2*K) - B*(n+nmodK)/K. In this sequence K=2,A=3,B=2, in A152204 K=2,A=2,B=1. %C A209634 No triangle with primes in every column, shifted down by K>=2 in OEIS, no row sums of it in OEIS. %C A209634 From _Johannes W. Meijer_, Sep 28 2013: (Start) %C A209634 Triangle read by rows formed from antidiagonals of triangle A143971. %C A209634 The alternating row sums equal A004524(n+2) + 2*A004524(n+1). %C A209634 The antidiagonal sums equal A171452(n+1). (End) %F A209634 From _Johannes W. Meijer_, Sep 28 2013: (Start) %F A209634 T(n, k) = 3*n - 6*k + 4, n >= 1 and 1 <= k <= floor((n+1)/2). %F A209634 T(n, k) = A143971(n-k+1, k), n >= 1 and 1 <= k <= floor((n+1)/2). (End) %e A209634 Triangle: %e A209634 1 %e A209634 4 %e A209634 7, 1 %e A209634 10, 4 %e A209634 13, 7, 1 %e A209634 16, 10, 4 %e A209634 19, 13, 7, 1 %e A209634 22, 16, 10, 4 %e A209634 25, 19, 13, 7, 1 %e A209634 28, 22, 16, 10, 4 %e A209634 ... %p A209634 T := (n, k) -> 3*n - 6*k + 4: seq(seq(T(n, k), k=1..floor((n+1)/2)), n=1..15); # _Johannes W. Meijer_, Sep 28 2013 %Y A209634 Cf. A008315, A011973, A102541, A122196, A122197, A128099, A152198, A152204, A173284, A207538. %Y A209634 Cf. (Related to triangle sums) A006578, A000217, A002620, A004524, A171452. %K A209634 nonn,easy,tabf %O A209634 1,2 %A A209634 _Ctibor O. Zizka_, Mar 11 2012