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 A109317 Column 0 of triangle T=A109316 where T(n,k) = [T^2](n-1,k) + [T^2](n-2,k-1) and T^2 is the matrix square of T. 3
 1, 1, 2, 6, 22, 94, 446, 2294, 12542, 71974, 429342, 2643606, 16710382, 107980870, 710933118, 4756345750, 32265548622, 221540438502, 1537355395934, 10768777480374, 76063545106670, 541277072787334, 3877624448977150 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Table of n, a(n) for n=0..22. PROG (PARI) {a(n)=local(A=Mat(1), B); for(m=1, n+1, B=matrix(m, m); for(i=1, m, for(j=1, i, if(j==i, B[i, j]=1, if(i==2, B[i, j]=1, B[i, j]=(A^2)[i-1, j]+if(j>1, (A^2)[i-2, j-1]))); )); A=B); return(A[n+1, 1])} CROSSREFS Cf. A109316 (triangle), A109318 (column 1), A109319 (row sums), A000108. Sequence in context: A374544 A374545 A150274 * A109153 A030453 A001861 Adjacent sequences: A109314 A109315 A109316 * A109318 A109319 A109320 KEYWORD nonn AUTHOR Paul D. Hanna, Jul 07 2005 STATUS approved

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Last modified July 14 18:52 EDT 2024. Contains 374323 sequences. (Running on oeis4.)