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.

A337728 a(n) = (4*n+1)! * Sum_{k=0..n} 1 / (4*k+1)!.

Original entry on oeis.org

1, 121, 365905, 6278929801, 358652470233121, 51516840824285500441, 15640512874253077933887601, 8915467710633236496186345872425, 8755702529258688898174686554391144001, 13878488965077362598718732163634314533105081, 33731389859841228248933904149069928786421237268881
Offset: 0

Views

Author

Ilya Gutkovskiy, Sep 17 2020

Keywords

Crossrefs

Programs

  • Mathematica
    Table[(4 n + 1)! Sum[1/(4 k + 1)!, {k, 0, n}], {n, 0, 10}]
    Table[(4 n + 1)! SeriesCoefficient[(1/2) (Sin[x] + Sinh[x])/(1 - x^4), {x, 0, 4 n + 1}], {n, 0, 10}]
    Table[Floor[(1/2) (Sin[1] + Sinh[1]) (4 n + 1)!], {n, 0, 10}]
  • PARI
    a(n) = (4*n+1)!*sum(k=0, n, 1/(4*k+1)!); \\ Michel Marcus, Sep 17 2020

Formula

E.g.f.: (1/2) * (sin(x) + sinh(x)) / (1 - x^4) = x + 121*x^5/5! + 365905*x^9/9! + 6278929801*x^13/13! + ...
a(n) = floor(c * (4*n+1)!), where c = (sin(1) + sinh(1)) / 2 = A334363.

A334364 Decimal expansion of Sum_{k>=0} 1/(4*k+2)!.

Original entry on oeis.org

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

Views

Author

Ilya Gutkovskiy, Apr 24 2020

Keywords

Examples

			1/2! + 1/6! + 1/10! + ... = 0.5013891644735520305...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[(Cosh[1] - Cos[1])/2, 10, 110] [[1]]
  • PARI
    suminf(k=0, 1/(4*k+2)!) \\ Michel Marcus, Apr 25 2020

Formula

Equals (cosh(1) - cos(1))/2.

A334365 Decimal expansion of Sum_{k>=0} 1/(4*k+3)!.

Original entry on oeis.org

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

Views

Author

Ilya Gutkovskiy, Apr 24 2020

Keywords

Examples

			1/3! + 1/7! + 1/11! + ... = 0.1668651044179524751...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[(Sinh[1] - Sin[1])/2, 10, 111] [[1]]
  • PARI
    suminf(k=0, 1/(4*k+3)!) \\ Michel Marcus, Apr 25 2020

Formula

Equals (sinh(1) - sin(1))/2.

A349089 a(n) = n! * Sum_{k=0..floor((n-1)/4)} 1 / (4*k+1)!.

Original entry on oeis.org

0, 1, 2, 6, 24, 121, 726, 5082, 40656, 365905, 3659050, 40249550, 482994600, 6278929801, 87905017214, 1318575258210, 21097204131360, 358652470233121, 6455744464196178, 122659144819727382, 2453182896394547640, 51516840824285500441, 1133370498134281009702
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 25 2022

Keywords

Crossrefs

Programs

  • Mathematica
    Table[n! Sum[1/(4 k + 1)!, {k, 0, Floor[(n - 1)/4]}], {n, 0, 22}]
    nmax = 22; CoefficientList[Series[(Sin[x] + Sinh[x])/(2 (1 - x)), {x, 0, nmax}], x] Range[0, nmax]!

Formula

E.g.f.: (sin(x) + sinh(x)) / (2*(1 - x)).
a(n) = floor(c * n!) for n > 0, where c = 1.008336089... = A334363.
Showing 1-4 of 4 results.