A136225 - OEIS

A136225

Matrix square of triangle A136220, read by rows.

1, 2, 1, 8, 4, 1, 49, 26, 6, 1, 414, 232, 54, 8, 1, 4529, 2657, 629, 92, 10, 1, 61369, 37405, 9003, 1320, 140, 12, 1, 996815, 627435, 153276, 22606, 2385, 198, 14, 1, 18931547, 12248365, 3031553, 450066, 47500, 3904, 266, 16, 1, 412345688, 273211787

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OFFSET

0,2

COMMENTS

Column 0 of this triangle = column 1 of square array A136217.

LINKS

Table of n, a(n) for n=0..46.

FORMULA

Let P=A136220, V=A136230, then column k of P^2 (this triangle) = column 0 of V^(k+1) while column j of V = column 0 of P^(3j+2).

EXAMPLE

Let P = A136220, then this triangle is P^2 and begins:

2, 1;

8, 4, 1;

49, 26, 6, 1;

414, 232, 54, 8, 1;

4529, 2657, 629, 92, 10, 1;

61369, 37405, 9003, 1320, 140, 12, 1;

996815, 627435, 153276, 22606, 2385, 198, 14, 1;

18931547, 12248365, 3031553, 450066, 47500, 3904, 266, 16, 1; ...

where column k of P^2 = column 0 of V^(k+1) and

triangle V = A136230 begins:

2, 1;

8, 5, 1;

49, 35, 8, 1;

414, 325, 80, 11, 1;

4529, 3820, 988, 143, 14, 1;

61369, 54800, 14696, 2200, 224, 17, 1; ...

where column k of V = column 0 of P^(3k+2).

Triangle P = A136220 begins:

1, 1;

3, 2, 1;

15, 10, 3, 1;

108, 75, 21, 4, 1;

1036, 753, 208, 36, 5, 1;

12569, 9534, 2637, 442, 55, 6, 1;

185704, 146353, 40731, 6742, 805, 78, 7, 1; ...

where column k of P = column 0 of U^(k+1) and U = A136228.

PROG

(PARI) {T(n, k)=local(P=Mat(1), U, PShR); if(n>0, for(i=0, n, PShR=matrix(#P, #P, r, c, if(r>=c, if(r==c, 1, if(c==1, 0, P[r-1, c-1])))); U=P*PShR^2; U=matrix(#P+1, #P+1, r, c, if(r>=c, if(r<#P+1, U[r, c], if(c==1, (P^3)[ #P, 1], (P^(3*c-1))[r-c+1, 1])))); P=matrix(#U, #U, r, c, if(r>=c, if(r<#R, P[r, c], (U^c)[r-c+1, 1]))))); (P^2)[n+1, k+1]}

CROSSREFS

Cf. columns: A136226, A136227; related tables: A136228 (U), A136230 (V), A136231 (W=P^3), A136217, A136218.

Sequence in context: A110171 A104988 A343296 * A341724 A089460 A308695

Adjacent sequences: A136222 A136223 A136224 * A136226 A136227 A136228

KEYWORD

nonn,tabl

AUTHOR

Paul D. Hanna, Jan 28 2008

STATUS

approved