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 A121427 Main diagonal of rectangular table A121426. 6
 1, 2, 15, 178, 2820, 55410, 1294776, 35003430, 1073540871, 36805249870, 1394346324624, 57831360118800, 2605921998840420, 126757491839620950, 6619466939158637640, 369368127676399990338, 21932876159270004129285 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Also main diagonal of square array A136737. LINKS FORMULA a(n) = [A121412^(n+1)](n+1,1) for n>=0; i.e., (n+1)-th term of column 1 in matrix power A121412^(n+1). PROG (PARI) {a(n)=local(H=Mat(1), B); for(m=1, n+2, B=matrix(m, m); for(i=1, m, for(j=1, i, if(j==i, B[i, j]=1, B[i, j]=(H^i)[i-1, j]); )); H=B); return((H^(n+1))[n+2, 2])} CROSSREFS Cf. A121426, A121412. Cf. A136737; A121413, A121417, A121422; A136741. Sequence in context: A036080 A215368 A200795 * A099709 A208409 A196792 Adjacent sequences:  A121424 A121425 A121426 * A121428 A121429 A121430 KEYWORD nonn AUTHOR Paul D. Hanna, Aug 26 2006 EXTENSIONS Edited by N. J. A. Sloane, Oct 30 2008 at the suggestion of R. J. Mathar STATUS approved

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