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 1-10 of 10 results.

A147871 Expansion of Product_{k > 0} (1 + A147665(k)*x^k).

Original entry on oeis.org

1, 1, 1, 3, 4, 7, 10, 15, 24, 37, 49, 73, 105, 142, 208, 294, 391, 538, 752, 988, 1359, 1812, 2410, 3232, 4270, 5598, 7454, 9721, 12639, 16625, 21445, 27649, 35793, 46235, 59141, 76215, 96975, 123262, 157671, 199625, 252591, 319792, 403262, 507682
Offset: 0

Views

Author

Roger L. Bagula, Nov 16 2008

Keywords

Examples

			From _Petros Hadjicostas_, Apr 11 2020: (Start)
Let f(m) = A147665(m). Using the strict partitions of each n (see A000009), we get
a(1) = f(1) = 1,
a(2) = f(2) = 1,
a(3) = f(3) + f(1)*f(2) = 2 + 1*1 = 3,
a(4) = f(4) + f(1)*f(3) = 2 + 1*2 = 4,
a(5) = f(5) + f(1)*f(4) + f(2)*f(3) = 3 + 1*2 + 1*2 = 7,
a(6) = f(6) + f(1)*f(5) + f(2)*f(4) + f(1)*f(2)*f(3) = 3 + 1*3 + 1*2 + 1*1*2 = 10,
a(7) = f(7) + f(1)*f(6) + f(2)*f(5) + f(3)*f(4) + f(1)*f(2)*f(4) = 3 + 1*3 + 1*3 + 2*2 + 1*1*2 = 15. (End)
		

Crossrefs

Programs

  • Mathematica
    (*A147665*) f[0] = 0; f[1] = 1; f[2] = 1; f[n_] := f[n] = f[f[n - 1]] + If[Mod[ n, 3] == 0, f[f[n/3]], If[Mod[n, 3] == 1, f[f[(n - 1)/3]], f[n - f[(n - 2)/3]]]];
    P[x_, n_] := P[x, n] = Product[1 + f[m]*x^m, {m, 0, n}];
    Take[CoefficientList[P[x, 45], x], 45] (* Program simplified by Petros Hadjicostas, Apr 13 2020 *)

Formula

a(n) = [x^n] Product_{k > 0} (1 + A147665(k)*x^k).
a(n) = Sum_{(b_1,...,b_n)} f(1)^b_1 * f(2)^b_2 * ... * f(n)^b_n, where f(m) = A147665(m), and the sum is taken over all lists (b_1,...,b_n) with b_j in {0,1} and Sum_{j=1..n} j*b_j = n. - Petros Hadjicostas, Apr 11 2020

Extensions

Various sections edited by Petros Hadjicostas, Apr 11 2020

A166497 A Per Bak sand pile collapse sequence using A147665 in the A153112 form.

Original entry on oeis.org

1, 1, 1, 1, 2, 3, 2, 2, 3, 2, 2, 3, 2, 2, 3, 2, 2, 4, 3, 2, 4, 3, 2, 4, 3, 2, 5, 1, 2, 2, 2, 2, 3, 2, 2, 4, 3, 2, 4, 3, 2, 4, 3, 2, 5, 4, 3, 5, 4, 2, 5, 5, 5, 5, 4, 3, 6, 3, 2, 4, 4, 4, 4, 3, 2, 5, 4, 3, 5, 5, 5, 6, 3, 2, 7, 3, 2, 4, 5, 6, 5, 4, 3, 4, 3, 2, 4, 3, 2, 4, 1, 2, 2, 2, 2, 3, 2, 2, 4, 3, 2, 4, 3, 2, 4
Offset: 0

Views

Author

Roger L. Bagula, Oct 15 2009

Keywords

References

  • Per Bak, "How nature works, the science of self-organized criticality", Springer-Verlag, New York, 1996, pages 49-64

Crossrefs

Programs

  • Mathematica
    f[0] = 1; f[1] = 1; f[2] = 1;
    f[n_] := f[n] = If[Mod[Floor[Sum[f[i], {i, 0, n - 1}]/2], 2^(4 + Mod[n, 3])] == 1, 1 + Mod[n, 3], f[f[n - 1]] + If[Mod[n, 3] == 0, f[f[n/3]], If[Mod[n, 3] == 1, f[f[(n - 1)/3]], f[n - f[(n - 2)/3]]]]];
    Table[f[n], {n, 0, 200}]

A147880 Expansion of Product_{k > 0} (1 + A005229(k)*x^k).

Original entry on oeis.org

1, 1, 1, 3, 5, 8, 12, 21, 30, 50, 75, 110, 169, 249, 361, 539, 757, 1076, 1583, 2207, 3121, 4415, 6184, 8468, 11775, 16274, 22314, 30601, 41745, 56412, 77008, 103507, 138383, 186928, 249855, 333375, 443898, 588402, 778276, 1031126, 1356945, 1780645
Offset: 0

Views

Author

Roger L. Bagula, Nov 16 2008

Keywords

Examples

			From _Petros Hadjicostas_, Apr 10 2020: (Start)
Let f(m) = A005229(m). Using the strict partitions of each n (see A000009), we get
a(1) = f(1) = 1,
a(2) = f(2) = 1,
a(3) = f(3) + f(1)*f(2) = 2 + 1*1 = 3,
a(4) = f(4) + f(1)*f(3) = 3 + 1*2 = 5,
a(5) = f(5) + f(1)*f(4) + f(2)*f(3) = 3 + 1*3 + 1*2 = 8,
a(6) = f(6) + f(1)*f(5) + f(2)*f(4) + f(1)*f(2)*f(3) = 4 + 1*3 + 1*3 + 1*1*2 = 12,
a(7) = f(7) + f(1)*f(6) + f(2)*f(5) + f(3)*f(4) + f(1)*f(2)*f(4) = 5 + 1*4 + 1*3 + 2*3 + 1*1*3 = 21. (End)
		

Crossrefs

Programs

  • Mathematica
    (*A005229*) f[n_Integer?Positive] := f[n] = f[ f[n - 2]] + f[n - f[n - 2]]; f[0] = 0; f[1] = f[2] = 1;
    P[x_, n_] := P[x, n] = Product[1 + f[m] *x^m, {m, 0, n}];
    Take[CoefficientList[P[x, 45], x], 45] (* Program simplified by Petros Hadjicostas, Apr 13 2020 *)
  • PARI
    \\ here B(n) is A005229 as vector.
    B(n)={my(a=vector(n, i, 1)); for(n=3, n, a[n] = a[a[n-2]] + a[n-a[n-2]]); a}
    seq(n)={my(v=B(n)); Vec(prod(k=1, n, 1 + v[k]*x^k + O(x*x^n)))} \\ Andrew Howroyd, Apr 10 2020

Formula

G.f.: Product_{k > 0} (1 + A005229(k)*x^k).
a(n) = Sum_{(b_1,...,b_n)} f(1)^b_1 * f(2)^b_2 * ... * f(n)^b_n, where f(m) = A005229(m), and the sum is taken over all lists (b_1,...,b_n) with b_j in {0,1} and Sum_{j=1..n} j*b_j = n.

Extensions

Various sections edited by Joerg Arndt and Petros Hadjicostas, Apr 10 2020

A147952 a(0) = 0, a(1) = a(2) = 1, and for n >= 3, a(n) = a(a(n-2)) + r(n), where r(n) = a(a(floor(n/3))) when n == 0 or 1 (mod 3) and = a(n - a(floor(n/3))) when n == 2 (mod 3).

Original entry on oeis.org

0, 1, 1, 2, 2, 3, 2, 3, 4, 3, 3, 5, 3, 4, 5, 4, 5, 7, 4, 4, 6, 4, 4, 8, 4, 6, 6, 4, 4, 8, 4, 6, 10, 5, 6, 7, 4, 5, 9, 5, 5, 8, 6, 7, 7, 5, 5, 10, 6, 6, 7, 5, 6, 8, 4, 6, 8, 4, 6, 8, 4, 6, 10, 4, 5, 8, 5, 6, 8, 6, 8, 6, 6, 4, 10, 4, 5, 8, 5, 6, 13, 4, 6, 8, 4, 6, 8, 6, 8, 6, 6, 4, 10, 4, 5, 8, 6, 7, 10, 6, 6
Offset: 0

Views

Author

Roger L. Bagula, Nov 17 2008

Keywords

Crossrefs

Programs

  • Mathematica
    f[0] = 0; f[1] = 1; f[2] = 1; f[n_] := f[n] = f[f[n - 2]] + If[Mod[n, 3] == 0,f[f[n/3]], If[Mod[n, 3] == 1, f[f[(n - 1)/3]], f[n - f[(n - 2)/3]]]]; Table[f[n], {n, 0, 100}]

Formula

a(n) = a(a(n - 2)) + If[Mod[n, 3] == 0, a(a(n/3)), If[Mod[n, 3] == 1, a(a((n - 1)/3)), a(n - a((n - 2)/3))] for n >= 3 with a(0) = 0 and a(1) = a(2) = 1. [edited by Petros Hadjicostas, Apr 13 2020]

Extensions

Name edited by Petros Hadjicostas, Apr 13 2020

A147953 Expansion of Product_{k > 0} (1 + f(k)*x^k), where f(n) = A147952(n).

Original entry on oeis.org

1, 1, 1, 3, 4, 7, 9, 14, 22, 32, 43, 61, 89, 118, 167, 235, 312, 417, 572, 748, 1006, 1326, 1744, 2283, 2982, 3878, 5048, 6518, 8355, 10786, 13727, 17436, 22173, 28250, 35561, 45008, 56651, 70818, 88992, 111280, 138431, 172284, 214019, 265166, 328127
Offset: 0

Views

Author

Roger L. Bagula, Nov 17 2008

Keywords

Crossrefs

Programs

  • Mathematica
    f[0] = 0; f[1] = 1; f[2] = 1;
    f[n_] := f[n] = f[f[n - 2]] + If[Mod[n, 3] == 0,f[f[n/3]], If[Mod[n, 3] == 1, f[f[(n - 1)/3]], f[n - f[(n - 2)/3]]]];
    P[x_, n_] := P[x, n] = Product[1 + f[m] x^m, {m, 0, n}];
    Take[CoefficientList[P[x, 45], x],45]
    (* Program edited and corrected by Petros Hadjicostas, Apr 12 2020 *)

Formula

a(n) = [x^n] Product_{k > 0} (1 + f(k)*x^k), where f(1) = f(2) = 1, and for m >= 3, f(m) = f(f(m-2)) + r(m), where r(m) = f(f(floor(m/3)) when m == 0 or 1 (mod 3) and = f(m - f(floor(m/3))) when m == 2 (mod 3).

Extensions

Various sections edited by Petros Hadjicostas, Apr 12 2020

A147954 a(0) = 0, a(1) = a(2) = 1, a(n) = a(a(n-1)) + a(n-a(n-1)) for 3 <= n <= 5, and a(n) = a(a(n-1)) + r(n) for n >= 6, where r(n) = a(a(floor(n/6))) for n == 0, 1, 2, 3, 4 (mod 6), and r(n) = a(n - a(floor(n/6))) for n == 5 (mod 6).

Original entry on oeis.org

0, 1, 1, 2, 2, 3, 3, 3, 3, 3, 3, 5, 4, 3, 3, 3, 3, 5, 4, 3, 3, 3, 3, 5, 4, 3, 3, 3, 3, 5, 5, 5, 5, 5, 5, 8, 5, 5, 5, 5, 5, 8, 5, 5, 5, 5, 5, 8, 5, 5, 5, 5, 5, 8, 5, 5, 5, 5, 5, 8, 5, 5, 5, 5, 5, 8, 6, 6, 6, 6, 6, 9, 5, 5, 5, 5, 5, 8, 5, 5, 5, 5, 5, 8, 5, 5, 5
Offset: 0

Views

Author

Roger L. Bagula, Nov 17 2008

Keywords

Crossrefs

Programs

  • Maple
    a := proc(n) local v; option remember;
    if n = 0 then v := 0; end if;
    if n = 1 or n = 2 then v := 1; end if;
    if 3 <= n and n <= 5 then v := a(a(n - 1)) + a(n - a(n - 1)); end if;
    if 6 <= n and 5 <> n mod 6 then v := a(a(n - 1)) + a(a(floor(n/6))); end if;
    if 6 <= n and 5 = n mod 6 then v := a(a(n - 1)) + a(n - a(floor(n/6))); end if; v; end proc; # Petros Hadjicostas, Apr 21 2020
  • Mathematica
    f[0] = 0; f[1] = 1; f[2] = 1;
    f[n_] := f[n] =
      f[f[n - 1]] +
       If[n < 6, f[n - f[n - 1]],
        If[Mod[n, 6] == 0, f[f[n/6]],
         If[Mod[n, 6] == 1, f[f[(n - 1)/6]],
          If[Mod[n, 6] == 2, f[f[(n - 2)/6]],
           If[Mod[n, 6] == 3, f[f[(n - 3)/6]],
            If[Mod[n, 6] == 4, f[f[(n - 4)/6]], f[n - f[(n - 5)/6]]]]]]]];
    Table[f[n], {n, 0, 300}]

Extensions

Name, data, and Mathematica program edited and corrected by Petros Hadjicostas, Apr 21 2020

A147955 Expansion of Product_{k >= 0} (1 + A147954(k)*x^k).

Original entry on oeis.org

1, 1, 1, 3, 4, 7, 10, 15, 22, 34, 46, 65, 93, 123, 175, 245, 324, 425, 592, 764, 1015, 1352, 1750, 2266, 2931, 3793, 4897, 6259, 7930, 10080, 12788, 16047, 20176, 25482, 31641, 39630, 49306, 60932, 75552, 93432, 114597, 141013, 173259, 211595, 258933, 316375, 384359, 466927, 566443
Offset: 0

Views

Author

Roger L. Bagula, Nov 17 2008

Keywords

Examples

			From _Petros Hadjicostas_, Apr 21 2020: (Start)
Let f(m) = A147954(m). Using the strict partitions of n (see A000009), we get:
a(1) = f(1) = 1,
a(2) = f(2) = 1,
a(3) = f(3) + f(1)*f(2) = 2 + 1*1 = 3,
a(4) = f(4) + f(1)*f(3) = 2 + 1*2 = 4,
a(5) = f(5) + f(1)*f(4) + f(2)*f(3) = 3 + 1*2 + 1*2 = 7,
a(6) = f(6) + f(1)*f(5) + f(2)*f(4) + f(1)*f(2)*f(3) = 3 + 1*3 + 1*2 + 1*1*2 = 10,
a(7) = f(7) + f(1)*f(6) + f(2)*f(5) + f(3)*f(4) + f(1)*f(2)*f(4) = 3 + 1*3 + 1*3 + 2*2 + 1*1*2 = 15. (End)
		

Crossrefs

Programs

  • Maple
    f := proc(n) local v; option remember;
    if n = 0 then v := 0; end if;
    if n = 1 or n = 2 then v := 1; end if;
    if 3 <= n and n <= 5 then v := f(f(n - 1)) + f(n - f(n - 1)); end if;
    if 6 <= n and 5 <> n mod 6 then v := f(f(n - 1)) + f(f(floor(n/6))); end if;
    if 6 <= n and 5 = n mod 6 then v := f(f(n - 1)) + f(n - f(floor(n/6))); end if; v; end proc; # this gives sequence A147954
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          b(n, i-1) +`if`(i>n, 0, b(n-i, i-1)*f(i))))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..50); # Petros Hadjicostas, Apr 21 2020 (using Alois P. Heinz's program from A147655)
  • Mathematica
    f[0] = 0; f[1] = 1; f[2] = 1;
    f[n_] := f[n] =
       f[f[n - 1]] +
        If[n < 6, f[n - f[n - 1]],
         If[Mod[n, 6] == 0, f[f[n/6]],
          If[Mod[n, 6] == 1, f[f[(n - 1)/6]],
           If[Mod[n, 6] == 2, f[f[(n - 2)/6]],
            If[Mod[n, 6] == 3, f[f[(n - 3)/6]],
             If[Mod[n, 6] == 4, f[f[(n - 4)/6]], f[n - f[(n - 5)/6]]]]]]]];
    P[x_, n_] := P[x, n] = Product[1 + f[m]*x^m, {m, 0, n}];
    Take[CoefficientList[P[x, 45], x], 45]

Formula

a(n) = [x^n] Product_{k >= 0} (1 + A147954(k)*x^k).
a(n) = Sum_{(b_1,...,b_n)} f(1)^b_1 * f(2)^b_2 * ... * f(n)^b_n, where f(m) = A147954(m), and the sum is taken over all lists (b_1,...,b_n) with b_j in {0,1} and Sum_{j=1..n} j*b_j = n. - Petros Hadjicostas, Apr 21 2020

Extensions

Name, data, and Mathematica program edited and corrected by Petros Hadjicostas, Apr 21 2020

A147879 Expansion of Product_{k>=1} (1 + x^k*A005185(k)).

Original entry on oeis.org

1, 1, 1, 3, 5, 8, 12, 21, 29, 49, 73, 105, 162, 236, 338, 502, 706, 984, 1441, 1998, 2800, 3934, 5472, 7407, 10210, 14053, 19066, 25986, 35134, 47010, 63739, 85008, 112610, 150861, 200133, 264838, 349587, 459970, 602763, 792220, 1034136, 1345530
Offset: 0

Views

Author

Roger L. Bagula, Nov 16 2008

Keywords

Crossrefs

Programs

  • Mathematica
    f[n_Integer?Positive] := f[n] = f[n - f[n - 1]] + f[n - f[n - 2]]; f[0] = 0; f[1] = f[2] = 1; (* A005185 *)
    nmax = 41; CoefficientList[Series[Product[(1 + f[k] * x^k), {k, 1, nmax}], {x, 0, nmax}], x] (* Georg Fischer, Dec 10 2020 *)
  • PARI
    \\ here B(n) is A005185 as vector.
    B(n)={my(A=vector(n, k, 1)); for(k=3, n, A[k]= A[k-A[k-1]]+ A[k-A[k-2]]); A}
    seq(n)=my(v=B(n)); {Vec(prod(k=1, #v, 1 + x^k*v[k] + O(x*x^n)))} \\ Andrew Howroyd, Dec 10 2020

Extensions

Definition corrected by Georg Fischer, Dec 10 2020

A152006 Expansion of Product_{k > 0} (1 + f(k)*x^k), where f(1) = 1 and f(m) = prime(m-1) for m >= 2.

Original entry on oeis.org

1, 1, 2, 5, 8, 18, 34, 63, 102, 203, 336, 589, 999, 1675, 2799, 4768, 7561, 12224, 20513, 31724, 51621, 81976, 128560, 199192, 312536, 482806, 744847, 1147952, 1755931, 2649474, 4051413, 6069450, 9105323, 13747364, 20335077, 30508629, 45198631
Offset: 0

Views

Author

Roger L. Bagula, Nov 19 2008

Keywords

Crossrefs

Programs

  • Mathematica
    f[n_] = If[n < 2, n, Prime[n - 1]];
    P[x_, n_] := P[x, n] = Product[1 + f[m]*x^m, {m, 0, n}];
    Take[CoefficientList[P[x, 37], x],37]
    (* Program edited and corrected by Petros Hadjicostas, Apr 12 2020 *)

Formula

a(n) = [x^n] Product_{k > 0} (1 + f(k)*x^k), where f(1) = 1 and f(m) = prime(m-1) for m >= 2.

Extensions

Various sections edited by Petros Hadjicostas, Apr 12 2020

A174231 A chaotic designed sequence with modulo six depth if ladder.

Original entry on oeis.org

0, 1, 1, 2, 2, 3, 3, 4, 5, 6, 6, 6, 4, 6, 9, 12, 8, 8, 6, 9, 15, 16, 12, 8, 6, 11, 21, 24, 10, 9, 8, 17, 14, 17, 23, 14, 11, 14, 33, 28, 14, 15, 14, 19, 17, 29, 18, 12, 7, 18, 25, 28, 34, 34, 26, 37, 22, 27, 35, 28, 13, 23, 26, 35, 47, 20, 18, 18, 31, 45, 57, 48, 9, 17, 28, 45, 36, 25, 14
Offset: 0

Views

Author

Roger L. Bagula, Mar 13 2010

Keywords

Comments

Programmed during one of my OEIS banned period and never entered.

Crossrefs

Programs

  • Mathematica
    f[0] = 0; f[1] = 1; f[2] = 1;
    f[n_] := f[n] = f[f[n - 1]] +
    If[n < 6, f[n - f[(n - 1)]], If[ Mod[n, 6] == 0, f[f[n/6]],
    If[Mod[1 + n, 6] == 1, f[f[(n - 1)/6]], If[Mod[2 + n, 6] == 2,
    f[f[(n - 2)/6]], If[Mod[3 + n, 6] == 3, f[f[(n - 3)/6]],
    If[Mod[4 + n, 6] == 4, f[f[(n - 4)/6]],
    If[ Mod[5 + n, 6] == 5, f[f[(n - 5)/6]], f[n - f[(n - 2)]]]]]]]]];
    Table[f[n], {n, 0, 100}]
Showing 1-10 of 10 results.