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 A121397 Column 2 of triangle T=A121395, where column k of T equals column k of T^(2^k) shift down 1 row. 2
 1, 1, 4, 22, 164, 1837, 34176, 1106012, 63053480, 6385424679, 1160549661044, 382452061644152, 230599430810507856, 256385360437413619926, 529174935800200166078372, 2039277788771681728279205788 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Also equals column 2 (shifted 1 place) of the matrix 4th power of triangle A121395. LINKS PROG (PARI) {a(n)=local(A=Mat(1), B); for(m=1, n+3, B=matrix(m, m); for(i=1, m, for(j=1, i, if(j==i, B[i, j]=1, B[i, j]=(A^(2^(j-1)))[i-1, j]); )); A=B); return(A[n+3, 3])} CROSSREFS Cf. A121395 (triangle), A121396 (column 1). Sequence in context: A111343 A302908 A187123 * A067369 A247249 A113351 Adjacent sequences:  A121394 A121395 A121396 * A121398 A121399 A121400 KEYWORD nonn AUTHOR Paul D. Hanna, Jul 27 2006 STATUS approved

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Last modified May 13 16:56 EDT 2021. Contains 343862 sequences. (Running on oeis4.)