A055068 - OEIS

A055068

Triangular array for David G. Cantor's sigma function.

1, 1, 1, 1, 2, 1, 1, 3, 4, 3, 1, 4, 10, 24, 10, 1, 5, 20, 105, 160, 105, 1, 6, 35, 336, 1260, 3360, 1260, 1, 7, 56, 882, 6720, 48510, 80640, 48510, 1, 8, 84, 2016, 27720, 443520, 2162160, 6209280, 2162160, 1, 9, 120, 4158, 95040, 2972970, 34594560, 312161850

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OFFSET

0,5

LINKS

Table of n, a(n) for n=0..52.

D. G. Cantor, On the analogue of the division polynomials for hyperelliptic curves, J. Reine Angew. Math. (Crelle's J.) 447 (1994), pp. 91-145.

FORMULA

T(n, k)*T(n-2, k-1)-2*T(n-1, k-1)*T(n-1, k)+T(n, k-1)*T(n-2, k)=0.

EXAMPLE

Triangle rows:

1,1;

1,2,1;

1,3,4,3;

1,4,10,24,10;

1,5,20,105,160,105;

...

PROG

(PARI) {T(n, k) = if( k<0 || k>n, 0, prod( i=1, (k+1)\2, binomial(n + 2*i - 1 - k%2, 4*i - 1 - k%2*2)))}

CROSSREFS

Sequence in context: A025564 A052265 A306565 * A237498 A319516 A015138

Adjacent sequences: A055065 A055066 A055067 * A055069 A055070 A055071

KEYWORD

nonn,tabl,easy

AUTHOR

Michael Somos, Jun 12 2000

STATUS

approved