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.

A101845 Triangle formed by left half of A101842, read by rows.

Original entry on oeis.org

1, 1, 3, 1, 7, 16, 1, 15, 61, 115, 1, 31, 206, 626, 1056, 1, 63, 659, 2989, 7554, 11774, 1, 127, 2052, 13308, 47349, 105099, 154624, 1, 255, 6297, 56935, 274677, 824331, 1660957, 2337507, 1, 511, 19162, 237862, 1518478, 5960818, 15747154, 29428654
Offset: 1

Views

Author

David Applegate, Jun 19 2007

Keywords

Examples

			Triangle begins:
  1,
  1,  3,
  1,  7,  16,
  1, 15,  61,  115,
  1, 31, 206,  626, 1056,
  1, 63, 659, 2989, 7554, 11774,
  ...
		

Crossrefs

Cf. A101842.

Programs

  • Maple
    A101842 := proc(n,k) option remember ; if k < -n or k >= n then 0 ; elif n = 1 then 1; else (n-k)*A101842(n-1,k-1)+A101842(n-1,k)+(n+k+1)*A101842(n-1,k+1) ; fi ; end: A101845 := proc(n,k) A101842(n,-n+k-1) ; end: for n from 1 to 10 do for k from 1 to n do printf("%d, ",A101845(n,k)) ; od: od: # R. J. Mathar, Aug 07 2007
  • Mathematica
    (* T is A101842 *)
    T[n_, k_] /; -n <= k <= n-1 := T[n, k] = (n-k)*T[n-1, k-1]+T[n-1, k]+(n+k+1)* T[n-1, k+1];
    T[1, -1] = T[1, 0] = 1; T[, ] = 0;
    A101845[n_, k_] := T[n, k-n-1];
    Table[A101845[n, k], {n, 1, 10}, {k, 1, n}] // Flatten (* Jean-François Alcover, Nov 17 2024 *)

Extensions

More terms from R. J. Mathar, Aug 07 2007

A102012 Triangle formed by right half of A101842, read by rows.

Original entry on oeis.org

1, 3, 1, 16, 7, 1, 115, 61, 15, 1, 1056, 626, 206, 31, 1, 11774, 7554, 2989, 659, 63, 1, 154624, 105099, 47349, 13308, 2052, 127, 1, 2337507, 1660957, 824331, 274677, 56935, 6297, 255, 1, 39984640, 29428654, 15747154, 5960818, 1518478, 237862
Offset: 1

Views

Author

David Applegate, Jun 19 2007

Keywords

Examples

			Triangle begins:
1
3, 1
16, 7, 1
115, 61, 15, 1
1056, 626, 206, 31, 1
11774, 7554, 2989, 659, 63, 1
		

Programs

  • Maple
    A101842 := proc(n,k) option remember ; if k < -n or k >= n then 0 ; elif n = 1 then 1; else (n-k)*A101842(n-1,k-1)+A101842(n-1,k)+(n+k+1)*A101842(n-1,k+1) ; fi ; end: A102012 := proc(n,k) A101842(n,k-1) ; end: for n from 1 to 10 do for k from 1 to n do printf("%d, ",A102012(n,k)) ; od: od: # R. J. Mathar, Aug 07 2007

Extensions

More terms from R. J. Mathar, Aug 07 2007

A373657 Triangle read by rows: Coefficients of the polynomials P(n, x) * EP(n, x), where P denote the signed Pascal polynomials and EP the Eulerian polynomials A173018.

Original entry on oeis.org

1, -1, 1, 1, -1, -1, 1, -1, -1, 8, -8, 1, 1, 1, 7, -27, 19, 19, -27, 7, 1, -1, -21, 54, 54, -276, 276, -54, -54, 21, 1, 1, 51, -25, -675, 1650, -1002, -1002, 1650, -675, -25, 51, 1, -1, -113, -372, 3436, -5125, -5013, 21216, -21216, 5013, 5125, -3436, 372, 113, 1
Offset: 0

Views

Author

Peter Luschny, Jun 15 2024

Keywords

Examples

			Triangle starts:
[0] [ 1]
[1] [-1,   1]
[2] [ 1,  -1,  -1,    1]
[3] [-1,  -1,   8,   -8,    1,     1]
[4] [ 1,   7, -27,   19,   19,   -27,     7,    1]
[5] [-1, -21,  54,   54, -276,   276,   -54,  -54,   21,   1]
[6] [ 1,  51, -25, -675, 1650, -1002, -1002, 1650, -675, -25, 51, 1]
		

Crossrefs

Cf. A173018, A049061, A101842, A000007 (row sums).

Programs

  • Maple
    PolyProd := proc(P, Q, len) local ep, eq, epq, CL, n, k;
    ep := (n, x) -> simplify(add(Q(n, k)*x^k, k = 0..n)):
    eq := (n, x) -> simplify(add(P(n, k)*x^k, k = 0..n)):
    epq := (n, x) -> expand(ep(n, x) * eq(n, x)):
    CL := p -> PolynomialTools:-CoefficientList(p, x);
    seq(CL(epq(n, x)), n = 0..len); ListTools:-Flatten([%]) end:
    PolyProd((n, k) -> (-1)^(n-k)*binomial(n, k), combinat:-eulerian1, 7);
Showing 1-3 of 3 results.