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 A134574 #22 Aug 08 2018 04:31:08
%S A134574 1,2,2,3,8,3,4,24,18,4,5,64,81,32,5,6,160,324,192,50,6,7,384,1215,
%T A134574 1024,375,72,7,8,896,4374,5120,2500,648,98,8,9,2048,15309,24576,15625,
%U A134574 5184,1029,128,9,10,4608,52488,114688,93750,38880,9604,1536,162,10
%N A134574 Array, a(n,k) = total size of all n-length words on a k-letter alphabet, read by antidiagonals.
%F A134574 a(n,k) = n*k^n.
%F A134574 O.g.f. (by columns): (k*x)/(-1+k*x)^2.
%F A134574 E.g.f. (by columns): k*x*exp(k*x).
%F A134574 a(n,k) = Sum[k^n,{j,1,n}] = n*Sum[C(n,m)*(k-1)^m,{m,0,n}]. - _Ross La Haye_, Jan 26 2008
%e A134574 a(2,2) = 8 because there are 2^2 = 4 2-length words on a 2 letter alphabet, each of size 2 and 2*4 = 8.
%e A134574 Array begins:
%e A134574 ==================================================================
%e A134574 n\k| 1 2 3 4 5 6 7 ...
%e A134574 ---|--------------------------------------------------------------
%e A134574 1 | 1 2 3 4 5 6 7 ...
%e A134574 2 | 2 8 18 32 50 72 98 ...
%e A134574 3 | 3 24 81 192 375 648 1029 ...
%e A134574 4 | 4 64 324 1024 2500 5184 9604 ...
%e A134574 5 | 5 160 1215 5120 15625 38880 84035 ...
%e A134574 6 | 6 384 4374 24576 93750 279936 705894 ...
%e A134574 7 | 7 896 15309 114688 546875 1959552 5764801 ...
%e A134574 8 | 8 2048 52488 524288 3125000 13436928 46118408 ...
%e A134574 9 | 9 4608 177147 2359296 17578125 90699264 363182463 ...
%e A134574 ... - _Franck Maminirina Ramaharo_, Aug 07 2018
%t A134574 t[n_, k_] := Sum[k^n, {j, n}]; Table[ t[n - k + 1, k], {n, 10}, {k, n}] // Flatten (* _Robert G. Wilson v_, Aug 07 2018 *)
%Y A134574 Cf. a(n, 1) = a(1, k) = A000027(n); a(n, 2) = A036289(n); a(n, 3) = A036290(n); a(n, 4) = A018215(n); a(n, 5) = A036291(n); a(n, 6) = A036292(n); a(n, 7) = A036293(n); a(n, 8) = A036294(n); a(2, k) = A001105(k); a(3, k) = A117642(k); a(n, n) = A007778(n); a(n, n+1) = A066274(n+1): sum[a(i-1, n-i+1), {i, 1, n}] = A062807(n).
%K A134574 nonn,tabl
%O A134574 1,2
%A A134574 _Ross La Haye_, Jan 22 2008