cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A305401 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where A(n,k) is Sum_{j=0..floor(n/2)} ((n-j)!/j!)*binomial(n-j,j)*k^(n-2*j).

Original entry on oeis.org

1, 1, 0, 1, 1, 1, 1, 2, 3, 0, 1, 3, 9, 10, 1, 1, 4, 19, 56, 43, 0, 1, 5, 33, 174, 457, 225, 1, 1, 6, 51, 400, 2107, 4626, 1393, 0, 1, 7, 73, 770, 6433, 31779, 55969, 9976, 1, 1, 8, 99, 1320, 15451, 129060, 574129, 788192, 81201, 0, 1, 9, 129, 2086, 31753, 387045, 3103873, 12088488, 12667041, 740785, 1
Offset: 0

Views

Author

Seiichi Manyama, Jun 02 2018

Keywords

Examples

			Square array begins:
   1,  1,   1,    1,    1,     1, ...
   0,  1,   2,    3,    4,     5, ...
   1,  3,   9,   19,   33,    51, ...
   0, 10,  56,  174,  400,   770, ...
   1, 43, 457, 2107, 6433, 15451, ...
		

Crossrefs

Columns k=0-3 give A059841, A001040(n+1), A036243, A305459.
Rows n=0-2 give A000012, A001477, A058331.
Main diagonal gives A305465.
Cf. A305466.

Formula

A(n,k) = k*n*A(n-1,k) + A(n-2,k) for n>1.

A305467 a(n) = Sum_{k=0..floor(n/2)} ((n-k)!/k!)*binomial(n-k,k)*n^(n-2*k)*(-1)^k.

Original entry on oeis.org

1, 1, 7, 150, 5857, 363045, 32817311, 4078256168, 667231014401, 139047475691385, 35961972186044999, 11303290914120251574, 4243674498966718214113, 1875719852330658989518045, 964140893268009386931042943, 570249392860305817156465883040
Offset: 0

Views

Author

Seiichi Manyama, Jun 02 2018

Keywords

Crossrefs

Main diagonal of A305466.
Cf. A305465.

Programs

  • PARI
    {a(n) = sum(k=0, n/2, ((n-k)!/k!)*binomial(n-k, k)*n^(n-2*k)*(-1)^k)}

Formula

a(n) ~ n! * n^n. - Vaclav Kotesovec, Jun 03 2018

A305471 a(0) = 1, a(1) = 3, a(n) = 3*n*a(n-1) - a(n-2).

Original entry on oeis.org

1, 3, 17, 150, 1783, 26595, 476927, 9988872, 239256001, 6449923155, 193258438649, 6371078552262, 229165569442783, 8931086129716275, 374876451878640767, 16860509248409118240, 808929567471759034753, 41238547431811301654163
Offset: 0

Views

Author

Seiichi Manyama, Jun 02 2018

Keywords

Comments

Let S(i,j,n) denote a sequence of the form a(0) = 1, a(1) = i, a(n) = i*n*a(n-1) + j*a(n-2). Then S(i,j,n) = Sum_{k=0..floor(n/2)} ((n-k)!/k!)*binomial(n-k,k)*i^(n-2*k)*j^k.

Crossrefs

Column k=3 of A305466.

Programs

  • PARI
    {a(n) = sum(k=0, n/2, ((n-k)!/k!)*binomial(n-k, k)*3^(n-2*k)*(-1)^k)}

Formula

a(n) = Sum_{k=0..floor(n/2)} ((n-k)!/k!)*binomial(n-k,k)*3^(n-2*k)*(-1)^k.
a(n) ~ BesselJ(0, 2/3) * n! * 3^n. - Vaclav Kotesovec, Jun 03 2018
Showing 1-3 of 3 results.