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 1-6 of 6 results.

A052251 Column 3 of A052250.

Original entry on oeis.org

1, 3, 6, 13, 27, 63, 148, 363, 912, 2330, 6036, 15825, 41865, 111636, 299736, 809513, 2197728, 5994219, 16416748, 45129396, 124479270, 344403494, 955557780, 2658061560, 7411457963, 20710700277, 57992124810, 162691293718, 457219737027, 1287065977413
Offset: 3

Views

Author

David Broadhurst, Feb 05 2000

Keywords

Comments

Also expansion of cube of g.f. for A051573. - Alois P. Heinz, Oct 23 2009

Crossrefs

Cf. A051573, A000081. - Alois P. Heinz, Oct 23 2009
Cf. A051491.

Programs

  • Maple
    with(numtheory): A81:= proc(n) option remember; `if`(n<2, n, (add(add(d*A81(d), d=divisors(j)) *A81(n-j), j=1..n-1))/ (n-1)) end: b:= proc(n) option remember; -`if`(n<0, 1, add(b(n-i) *A81(i+1), i=1..n+1)) end: B:= proc(n) add(b(i) *x^i, i=0..n) end: a:= n-> coeff(B(n)^3, x, n-3): seq(a(n), n=3..35); # Alois P. Heinz, Oct 23 2009
  • Mathematica
    A81[n_] := A81[n] = If[n < 2, n, Sum[Sum[d A81[d], {d, Divisors[j]}] A81[n - j], {j, 1, n - 1}]/(n - 1)];
    b[n_] := b[n] = -If[n < 0, 1, Sum[b[n - i] A81[i + 1], {i, 1, n + 1}]];
    B[n_] := Sum[b[i] x^i, {i, 0, n}];
    T[n_, k_] := Coefficient[B[n]^k, x, n - k];
    a[n_] := T[n, 3];
    a /@ Range[3, 35] (* Jean-François Alcover, Nov 09 2020, after Alois P. Heinz *)

Formula

a(n) ~ c * d^n / n^(3/2), where d = A051491 = 2.9557652856519949747148175241..., c = 0.195489104191039910520879642... . - Vaclav Kotesovec, Sep 05 2014

Extensions

More terms from Alois P. Heinz, Oct 23 2009

A052252 Column 4 of A052250.

Original entry on oeis.org

1, 4, 10, 24, 55, 132, 322, 804, 2051, 5304, 13886, 36716, 97882, 262756, 709658, 1926748, 5255707, 14396048, 39580338, 109190052, 302148814, 838449236, 2332652648, 6505071080, 18180441512, 50914047384, 142853059922, 401517522844, 1130400537667, 3187335556064
Offset: 4

Views

Author

David Broadhurst, Feb 05 2000

Keywords

Comments

Also expansion of 4th power of g.f. for A051573. - Alois P. Heinz, Oct 23 2009

Crossrefs

Cf. A051573, A000081. - Alois P. Heinz, Oct 23 2009

Programs

  • Maple
    with(numtheory): A81:= proc(n) option remember; `if`(n<2, n, (add(add(d*A81(d), d=divisors(j)) *A81(n-j), j=1..n-1))/ (n-1)) end: b:= proc(n) option remember; -`if`(n<0, 1, add(b(n-i) *A81(i+1), i=1..n+1)) end: B:= proc(n) add(b(i) *x^i, i=0..n) end: a:= n-> coeff(B(n)^4, x, n-4): seq(a(n), n=4..35); # Alois P. Heinz, Oct 23 2009
  • Mathematica
    A81[n_] := A81[n] = If[n < 2, n, Sum[Sum[d A81[d], {d, Divisors[j]}] A81[n - j], {j, 1, n - 1}]/(n - 1)];
    b[n_] := b[n] = -If[n < 0, 1, Sum[b[n - i] A81[i + 1], {i, 1, n + 1}]];
    B[n_] := Sum[b[i] x^i, {i, 0, n}];
    T[n_, k_] := Coefficient[B[n]^k, x, n - k];
    a[n_] := T[n, 4];
    a /@ Range[4, 35] (* Jean-François Alcover, Nov 09 2020, after Alois P. Heinz *)

Formula

a(n) ~ c * d^n / n^(3/2), where d = A051491 = 2.9557652856519949747148..., c = 0.17246782327675280347707... . - Vaclav Kotesovec, Sep 06 2014

Extensions

More terms from Alois P. Heinz, Oct 23 2009

A051573 INVERTi transform of A000081 = [1, 2, 4, 9, 20, 48, 115, 286, 719, 1842, 4766, 12486,...].

Original entry on oeis.org

1, 1, 1, 2, 3, 8, 16, 41, 98, 250, 631, 1646, 4285, 11338, 30135, 80791, 217673, 590010, 1606188, 4392219, 12055393, 33206321, 91752211, 254261363, 706465999, 1967743066, 5493195530, 15367129299, 43073007846, 120949992543, 340206026166, 958444631917
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Maple
    with(numtheory):
    b:= proc(n) option remember; local d, j; `if` (n<2, n,
          (add(add(d*b(d), d=divisors(j))*b(n-j), j=1..n-1))/(n-1))
        end:
    a:= proc(n) option remember; local i; `if`(n<0, -1,
          -add(a(n-i) *b(i+1), i=1..n+1))
        end:
    seq(a(n), n=0..40);  # Alois P. Heinz, May 17 2013
  • Mathematica
    b[n_] := b[n] = If[n < 2, n, Sum[Sum[d*b[d], {d, Divisors[j]}]*b[n-j], {j, 1, n-1}]/(n-1)]; a[n_] := a[n] = If[n < 0, -1, -Sum[a[n-i]*b[i+1], {i, 1, n+1}]]; Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Apr 16 2014, after Alois P. Heinz *)

Formula

a(n) ~ c * d^n / n^(3/2), where d = A051491 = 2.9557652856519949747148175241..., c = A187770 = 0.4399240125710253040409033914... . - Vaclav Kotesovec, Sep 06 2014

A051603 Expansion of square of g.f. for A051573.

Original entry on oeis.org

1, 2, 3, 6, 11, 26, 58, 142, 351, 890, 2282, 5948, 15624, 41442, 110703, 297676, 804892, 2187490, 5971392, 16366734, 45021391, 124253828, 343956858, 954760502, 2656946827, 7411140120, 20716895918, 58027609028, 162837485745
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Mathematica
    (* r = A000081 *) r[n_] := r[n] = If[n<2, n, Sum[DivisorSum[j, #*r[#]&] * r[n-j], {j, 1, n-1}]/(n-1)]; b[n_] := b[n] = -If[n<0, 1, Sum[b[n-i] * r[i+1], {i, 1, n+1}]]; B[n_] := Sum[b[i]*x^i, {i, 0, n}]; T[n_, k_] := Coefficient[B[n]^k, x, n-k]; a[n_] := T[n+2, 2]; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Mar 23 2017, after Alois P. Heinz *)

A052249 Triangle T(n,k) (n >= 1, k >= 1) giving dimension of bigrading of Connes-Moscovici noncocommutative algebra.

Original entry on oeis.org

1, 1, 1, 0, 2, 1, 0, 1, 3, 1, 0, 0, 2, 4, 1, 0, 0, 1, 4, 5, 1, 0, 0, 0, 2, 6, 6, 1, 0, 0, 0, 1, 4, 9, 7, 1, 0, 0, 0, 0, 2, 7, 12, 8, 1, 0, 0, 0, 0, 1, 4, 11, 16, 9, 1, 0, 0, 0, 0, 0, 2, 7, 16, 20, 10, 1, 0, 0, 0, 0, 0, 1, 4, 12, 23, 25, 11, 1, 0, 0, 0, 0, 0, 0, 2, 7, 18, 31, 30, 12, 1, 0, 0
Offset: 0

Views

Author

David Broadhurst, Feb 05 2000

Keywords

Comments

With rows reversed, T(n,k) appears to be the number of partitions of n with k big parts, where a big part is a part >= 2 (0 <= k <= n/2). For example, with n=4, the 3 partitions 4, 31, 211 each have one big part. - David Callan, Aug 23 2011

Examples

			Triangle begins
  1;
  1, 1;
  0, 2, 1;
  0, 1, 3, 1;
  0, 0, 2, 4, 1;
  0, 0, 1, 4, 5, 1;
  ...
		

Crossrefs

Cf. A052250.

Programs

  • Mathematica
    t[n_, k_] := Count[ IntegerPartitions[n], pp_ /; Count[pp, p_ /; p >= 2] == k]; Flatten[ Table[ t[n, k], {n, 1, 14}, {k, n-1, 0, -1} ] ] (* Jean-François Alcover, Jan 23 2012, after David Callan *)

A052253 Triangle T(n,k) (n >= 1, k >= 1) giving filtration of bigrading of Hopf algebra of rooted trees.

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 3, 3, 2, 1, 8, 5, 4, 2, 1, 16, 13, 9, 6, 3, 1, 41, 28, 21, 13, 8, 3, 1, 98, 71, 49, 33, 20, 10, 4, 1, 250, 174, 121, 79, 50, 27, 13, 4, 1, 631, 445, 304, 201, 127, 74, 38, 16, 5, 1, 1646, 1137, 776, 510, 325, 192, 106, 49, 19, 5, 1, 4285, 2974
Offset: 0

Views

Author

David Broadhurst, Feb 05 2000

Keywords

Examples

			1; 1,1; 2,1,1; 3,3,2,1; 8,5,4,2,1; ...
		

Crossrefs

Cf. A052250.
Showing 1-6 of 6 results.