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 1-5 of 5 results.

A191277 Expansion of e.g.f. 1/(1 - sinh(x)*cosh(x)).

Original entry on oeis.org

1, 1, 2, 10, 56, 376, 3152, 30640, 338816, 4226176, 58564352, 892337920, 14834994176, 267186021376, 5182147684352, 107689460377600, 2387077442011136, 56219583797886976, 1401949974947889152, 36902741817196871680, 1022494706646806429696
Offset: 0

Views

Author

Vladimir Kruchinin, May 29 2011

Keywords

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[1/(1-Sinh[x]*Cosh[x]), {x, 0, 20}], x]* Range[0, 20]! (* Vaclav Kotesovec, Jun 26 2013 *)
  • Maxima
    a(n):=sum(sum((-1)^i*(k-2*i)^n*binomial(k,i),i,0,k),k,1,n);
    
  • PARI
    my(x='x+O('x^30)); Vec(serlaplace(1/(1 - sinh(x)*cosh(x)))) \\ Michel Marcus, Jun 30 2022

Formula

a(n) = Sum_{k=1..n} Sum_{i=0..k} (-1)^i*(k-2*i)^n*binomial(k,i), n>0, a(0)=1.
a(n) ~ n! /(sqrt(5)*(log(2+sqrt(5))/2)^(n+1)). - Vaclav Kotesovec, Jun 26 2013
a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/2)} 4^k * binomial(n,2*k+1) * a(n-2*k-1). - Seiichi Manyama, Jun 30 2022

A381277 Expansion of e.g.f. exp(sinh(3*x) / 3).

Original entry on oeis.org

1, 1, 1, 10, 37, 172, 1477, 8416, 74377, 683344, 5836969, 67102048, 699721453, 8268521536, 107106298093, 1347611617792, 19462095444241, 279380302430464, 4247519795325649, 68946703997616640, 1122787065355425973, 19697500164381137920, 351304020205694058133
Offset: 0

Views

Author

Seiichi Manyama, Feb 18 2025

Keywords

Crossrefs

Programs

  • PARI
    a136630(n, k) = 1/(2^k*k!)*sum(j=0, k, (-1)^(k-j)*(2*j-k)^n*binomial(k, j));
    a(n) = sum(k=0, n, 3^(n-k)*a136630(n, k));

Formula

a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/2)} 9^k * binomial(n-1,2*k) * a(n-2*k-1).
a(n) = Sum_{k=0..n} 3^(n-k) * A136630(n,k).

A351891 Expansion of e.g.f. exp( sinh(sqrt(2)*x) / sqrt(2) ).

Original entry on oeis.org

1, 1, 1, 3, 9, 25, 105, 443, 1969, 10609, 57265, 338547, 2190969, 14498185, 104277849, 784965803, 6150938593, 51229928929, 440694547681, 3967606065891, 37247506348905, 361022009762809, 3645855348771273, 38001754007842715, 409302848055407761, 4558828622414199121
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 24 2022

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 25; CoefficientList[Series[Exp[Sinh[Sqrt[2] x]/Sqrt[2]], {x, 0, nmax}], x] Range[0, nmax]!
    a[0] = 1; a[n_] := a[n] = Sum[Binomial[n - 1, 2 k] 2^k a[n - 2 k - 1], {k, 0, Floor[(n - 1)/2]}]; Table[a[n], {n, 0, 25}]

Formula

a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/2)} binomial(n-1,2*k) * 2^k * a(n-2*k-1).
a(n) = Sum_{k=0..n} 2^((n-k)/2) * A136630(n,k). - Seiichi Manyama, Feb 20 2025

A351892 Expansion of e.g.f. exp( sinh(sqrt(3)*x) / sqrt(3) ).

Original entry on oeis.org

1, 1, 1, 4, 13, 40, 205, 952, 4921, 31168, 189145, 1318528, 9843781, 74869888, 632536933, 5475991552, 49996774897, 485393809408, 4829958877105, 50858117779456, 554544498995965, 6259096187060224, 73822470722135293, 894846287081242624, 11261265009125680681, 146272258394568687616
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 24 2022

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 25; CoefficientList[Series[Exp[Sinh[Sqrt[3] x]/Sqrt[3]], {x, 0, nmax}], x] Range[0, nmax]!
    a[0] = 1; a[n_] := a[n] = Sum[Binomial[n - 1, 2 k] 3^k a[n - 2 k - 1], {k, 0, Floor[(n - 1)/2]}]; Table[a[n], {n, 0, 25}]

Formula

a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/2)} binomial(n-1,2*k) * 3^k * a(n-2*k-1).
a(n) = Sum_{k=0..n} 3^((n-k)/2) * A136630(n,k). - Seiichi Manyama, Feb 20 2025

A381343 Expansion of e.g.f. exp( sin(sqrt(2)*x) / sqrt(2) ).

Original entry on oeis.org

1, 1, 1, -1, -7, -15, 25, 287, 721, -2847, -30255, -61697, 682761, 5861713, 3105193, -258188513, -1681060063, 4623681473, 135471132705, 564325398271, -6357495670375, -89817656595791, -84337394884167, 7820620314702879, 67277670159083761, -322108989883888479
Offset: 0

Views

Author

Seiichi Manyama, Feb 20 2025

Keywords

Crossrefs

Programs

  • PARI
    a136630(n, k) = 1/(2^k*k!)*sum(j=0, k, (-1)^(k-j)*(2*j-k)^n*binomial(k, j));
    a(n) = sum(k=0, n, (-2)^((n-k)/2)*a136630(n, k));

Formula

a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/2)} (-2)^k * binomial(n-1,2*k) * a(n-2*k-1).
a(n) = Sum_{k=0..n} (-2)^((n-k)/2) * A136630(n,k).
Showing 1-5 of 5 results.