A113387 - OEIS

A113387

Triangle, read by rows, equal to the matrix cube of A113381.

1, 6, 1, 48, 15, 1, 605, 255, 24, 1, 11196, 5630, 624, 33, 1, 280440, 159210, 19484, 1155, 42, 1, 8981460, 5584635, 731664, 46541, 1848, 51, 1, 353283128, 236051661, 32532732, 2173248, 91175, 2703, 60, 1, 16567072675, 11741443007, 1683566556

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..38.

FORMULA

Column k of A113381^3 = column 0 of A113389^(3*k+2) for k>=0.

EXAMPLE

Triangle A113381^3 begins:

6,1;

48,15,1;

605,255,24,1;

11196,5630,624,33,1;

280440,159210,19484,1155,42,1;

8981460,5584635,731664,46541,1848,51,1;

353283128,236051661,32532732,2173248,91175,2703,60,1;

16567072675,11741443007,1683566556,116647443,5086116,157760,3720,69,1;

PROG

(PARI) T(n, k)=local(A, B); A=Mat(1); for(m=2, n+1, B=matrix(m, m); for(i=1, m, for(j=1, i, if(i<3 || j==i || j>m-1, B[i, j]=1, if(j==1, B[i, 1]=1, B[i, j]=(A^(3*j-2))[i-j+1, 1])); )); A=B); (matrix(#A, #A, r, c, if(r>=c, (A^(3*c-1))[r-c+1, 1]))^3)[n+1, k+1]

CROSSREFS

Cf. A113381, A113388 (column 0), A113389.

Sequence in context: A138192 A136235 A113392 * A290316 A090435 A136237

Adjacent sequences: A113384 A113385 A113386 * A113388 A113389 A113390

KEYWORD

nonn,tabl

AUTHOR

Paul D. Hanna, Nov 14 2005

STATUS

approved