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 1-4 of 4 results.

A283536 Expansion of exp( Sum_{n>=1} -A283535(n)/n*x^n ) in powers of x.

Original entry on oeis.org

1, -1, -64, -19619, -16755517, -30499543213, -101528172949440, -558442022082754554, -4721800698082895269442, -58144976385942395405449505, -999941534906642496357956893139, -23224150593200781968944997552887957, -708778584588517237886357058373629079824
Offset: 0

Views

Author

Seiichi Manyama, Mar 10 2017

Keywords

Crossrefs

Cf. Product_{k>=1} (1 - x^k)^(k^(m*k)): A010815 (m=0), A283499 (m=1), A283534 (m=2), this sequence (m=3).
Cf. A283580 (Product_{k>=1} 1/(1 - x^k)^(k^(3*k))).

Programs

  • Mathematica
    A[n_] :=  Sum[d^(3*d + 1), {d, Divisors[n]}]; a[n_]:=If[n==0, 1, -(1/n)*Sum[A[k]*a[n - k], {k, n}]]; Table[a[n], {n, 0, 12}] (* Indranil Ghosh, Mar 11 2017 *)
  • PARI
    A(n) = sumdiv(n, d, d^(3*d + 1));
    a(n) = if(n==0, 1, -(1/n)*sum(k=1, n, A(k)*a(n - k)));
    for(n=0, 12, print1(a(n), ", ")) \\ Indranil Ghosh, Mar 11 2017

Formula

G.f.: Product_{k>=1} (1 - x^k)^(k^(3*k)).
a(n) = -(1/n)*Sum_{k=1..n} A283535(k)*a(n-k) for n > 0.

A283579 Expansion of exp( Sum_{n>=1} A283533(n)/n*x^n ) in powers of x.

Original entry on oeis.org

1, 1, 17, 746, 66418, 9843707, 2187941520, 680615139257, 282199700198462, 150389915598653924, 100155578743010743914, 81505577512720707466924, 79580089689432499741178617, 91814299713761739807846854872
Offset: 0

Views

Author

Seiichi Manyama, Mar 11 2017

Keywords

Crossrefs

Cf. Product_{k>=1} 1/(1 - x^k)^(k^(m*k)): A000041 (m=0), A023880 (m=1), this sequence (m=2), A283580 (m=3).
Cf. A283534 (Product_{k>=1} (1 - x^k)^(k^(2*k))).

Programs

  • Mathematica
    A[n_] :=  Sum[d^(2*d + 1), {d, Divisors[n]}]; a[n_] := If[n==0, 1, (1/n)*Sum[A[k]*a[n - k], {k, n}]]; Table[a[n], {n, 0, 13}] (* Indranil Ghosh, Mar 11 2017 *)
  • PARI
    A(n) = sumdiv(n, d, d^(2*d + 1));
    a(n) = if(n==0, 1, (1/n)*sum(k=1, n, A(k)*a(n - k)));
    for(n=0, 11, print1(a(n),", ")) \\ Indranil Ghosh, Mar 11 2017

Formula

G.f.: Product_{k>=1} 1/(1 - x^k)^(k^(2*k)).
a(n) = (1/n)*Sum_{k=1..n} A283533(k)*a(n-k) for n > 0.
a(n) ~ n^(2*n) * (1 + exp(-2)/n^2). - Vaclav Kotesovec, Mar 17 2017

A283674 Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is the expansion of Product_{j>=1} 1/(1-x^j)^(j^(k*j)) in powers of x.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 1, 5, 3, 1, 1, 17, 32, 5, 1, 1, 65, 746, 298, 7, 1, 1, 257, 19748, 66418, 3531, 11, 1, 1, 1025, 531698, 16799044, 9843707, 51609, 15, 1, 1, 4097, 14349932, 4295531890, 30535636881, 2187941520, 894834, 22, 1, 1, 16385, 387424586, 1099526502508, 95371863221411, 101591759812967, 680615139257, 17980052, 30
Offset: 0

Views

Author

Seiichi Manyama, Mar 14 2017

Keywords

Examples

			Square array begins:
   1,   1,     1,        1, ...
   1,   1,     1,        1, ...
   2,   5,    17,       65, ...
   3,  32,   746,    19748, ...
   5, 298, 66418, 16799044, ...
		

Crossrefs

Columns k=0-4 give A000041, A023880, A283579, A283580, A283510.
Rows give: 0-1: A000012, 2: A052539, 3: A283716.
Main diagonal gives A283719.
Cf. A283675.

Programs

  • Maple
    with(numtheory):
    A:= proc(n, k) option remember; `if`(n=0, 1, add(add(
          d*d^(k*d), d=divisors(j))*A(n-j, k), j=1..n)/n)
        end:
    seq(seq(A(n, d-n), n=0..d), d=0..10);  # Alois P. Heinz, Mar 15 2017
  • Mathematica
    A[n_, k_] := If[n==0, 1, Sum[Sum[d*d^(k*d), {d, Divisors[j]}] *A[n - j, k], {j, n}] / n]; Flatten[Table[A[d - n,  n],{d, 0, 10},{n, d, 0, -1}]] (* Indranil Ghosh, Mar 17 2017 *)
  • PARI
    A(n, k) = if(n==0, 1, sum(j=1, n, sumdiv(j, d, d*d^(k*d)) * A(n - j, k))/n);
    {for(d=0, 10, for(n=0, d, print1(A(n, d - n),", ");); print(););} \\ Indranil Ghosh, Mar 17 2017

Formula

G.f. of column k: Product_{j>=1} 1/(1-x^j)^(j^(k*j)).

A283510 Expansion of exp( Sum_{n>=1} A283369(n)/n*x^n ) in powers of x.

Original entry on oeis.org

1, 1, 257, 531698, 4295531890, 95371863221411, 4738477950914329100, 459991301719292572342573, 79228623778497392212453912974, 22528478894247280128054776211273960, 10000022549030658394108744658459680045250
Offset: 0

Views

Author

Seiichi Manyama, Mar 17 2017

Keywords

Crossrefs

Cf. Product_{k>=1} 1/(1 - x^k)^(k^(m*k)): A000041 (m=0), A023880 (m=1), A283579 (m=2), A283580 (m=3), this sequence (m=4).
Cf. A283803 (Product_{k>=1} (1 - x^k)^(k^(4*k))).

Programs

  • Mathematica
    CoefficientList[Series[Product[1/(1 - x^k)^(k^(4k)), {k, 1, 10}], {x, 0, 10}], x] (* Indranil Ghosh, Mar 17 2017 *)
  • PARI
    A(n) = sumdiv(n, d, d^(4*d + 1));
    a(n) = if(n<1, 1, (1/n) * sum(k=1, n, A(k) * a(n - k)));
    for(n=0, 10, print1(a(n),", ")) \\ Indranil Ghosh, Mar 17 2017

Formula

G.f.: Product_{k>=1} 1/(1 - x^k)^(k^(4*k)).
a(n) = (1/n)*Sum_{k=1..n} A283369(k)*a(n-k) for n > 0.
a(n) ~ n^(4*n) * (1 + exp(-4)/n^4). - Vaclav Kotesovec, Mar 17 2017
Showing 1-4 of 4 results.