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.

A287936 Numerator of moments of Rvachëv function up(x).

Original entry on oeis.org

1, 1, 19, 583, 132809, 46840699, 4068990560161, 1204567303451311, 4146897304424408411, 18814360006695807527868793, 21431473463327429953796293981397, 911368783375270623395381542054690099, 3805483535214088799368825731508632105336401423
Offset: 0

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Author

Juan Arias-de-Reyna, Jun 03 2017

Keywords

Comments

a(n)/A287937(n) is equal to the integral of t^(2n) * up(t), the moment of the Rvachëv function. The Rvachëv function is related to the Fabius function; up(x)=F(x+1) for |x|<1 and up(x)=0 for |x|>=1, where F is the Fabius function.

Crossrefs

Programs

  • Mathematica
    c[0] = 1;
    c[n_] := c[n] =
       Sum[Binomial[2 n + 1, 2 k] c[k], {k, 0, n - 1}]/((2 n + 1) (2^(2 n) - 1));
    Table[Numerator[c[n]], {n, 0, 30}]

Formula

Recurrence c(0)=1, c(n)=Sum_{k=0..n-1}(binomial(2n+1,2k) c_k)/((2n+1)*(2^(2n)-1)), where c(n)=a(n)/A287937(n).

A287938 Integers associated with moments of Rvachëv function.

Original entry on oeis.org

1, 1, 19, 2915, 2788989, 14754820185, 402830065455939, 54259734183964303995, 34931036957548128175343565, 104968042559556881090071537121985, 1445701512369903326110289606343988638195, 89942525814858602265845303890518923811304544595, 24979493321562411847493262443987087581059026281953954525
Offset: 0

Views

Author

Juan Arias-de-Reyna, Jun 03 2017

Keywords

Comments

a(n) is equal to the product of (2*n+1)!!*(Product_{k=1..n} (2^(2*k)-1)) and A287936(n)/A287937(n), the moment of the Rvachëv function. The Rvachëv function is related to the Fabius function; up(x)=F(x+1) for |x|<1 and up(x)=0 for |x|>=1, where F is the Fabius function.

Crossrefs

Programs

  • Mathematica
    c[0] = 1;
    c[n_] := c[n] =
       Sum[Binomial[2 n + 1, 2 k] c[k], {k, 0, n - 1}]/((2 n + 1) (2^(2 n) - 1));
    a[n_] := a[n] = c[n] (2 n + 1)!! Product[(2^(2 k) - 1), {k, 1, n}];
    Table[a[n], {n, 0, 30}]
    Table[(-1)^n 4^(-n) (2 n)! (2 n + 1)!! Sum[QBinomial[n, k, 1/4] 2^(-k (3 k + 1)/2)/(2 n + k + 1)! Sum[(-1)^ThueMorse[m] (2 m + 1)^(2 n + k + 1), {m, 0, 2^k - 1}], {k, 0, n}], {n, 0, 12}] (* Vladimir Reshetnikov, Jul 08 2018 *)

Formula

a(n) = (2*n+1)!!*(Product_{k=1..n} (2^(2*k)-1))*A287936(n)/A287937(n).

A288161 Denominator of half moments of Rvachëv function.

Original entry on oeis.org

2, 18, 6, 1350, 270, 23814, 17010, 65063250, 7229250, 9762090030, 4437313650, 8267713725521250, 635977978886250, 81188783595533250, 297692206516955250, 22510683177794610356250, 1564913803803903393750, 40011216302189267004656036250, 10529267447944543948593693750
Offset: 1

Views

Author

Juan Arias-de-Reyna, Jun 06 2017

Keywords

Comments

a(n) is equal to the denominator of the integral over (0,1) of n*t^(n-1)*up(t).
These numbers are the half moments of the Rvachëv function. The Rvachëv function is related to the Fabius function, up(x)=F(x+1) for |x|<1 and up(x)=0 for |x|>=1.
The sequence of numerators is not in the OEIS because it appears t coincide with A272755: Numerators of Fabius function F(1/2^n). In fact d(n) = n! 2^binomial(n,2)F(1/2^n). The coincidence depends on the fact that n! 2^binomial(n,2) divides the denominator of F(1/2^n). It is true that 2^binomial(n,2) divides this denominator, but I do not see any reason for n! to divide this denominator.

Examples

			The rationals d(n) are  1/2, 5/18, 1/6, 143/1350, 19/270,  ...
		

Crossrefs

Programs

  • Mathematica
    d[0] = 1;
    d[n_] := d[n] =
      Sum[Binomial[n + 1, k] d[k], {k, 0, n - 1}]/((n + 1)*(2^n - 1));
    Table[Denominator[d[n]], {n, 1, 20}]

Formula

Recurrence d(0)=1; d(n)=Sum_{k=0..n-1}(binomial(n+1,k)d(k))/((n+1)*(2^n-1)) with a(n) are the denominators of d(n).
It may also be defined to be the only sequence d(n) with d(0)=1 and such that the function f(x)=Sum_{n>=0} d(n) x^n/n! satisfies x*f(2x)=(e^x-1)*f(x).

A288163 Integers related to the half moments of Rvachëv function.

Original entry on oeis.org

1, 1, 5, 84, 4004, 494760, 150120600, 107969547840, 179605731622464, 678695382464158080, 5745964983105758544000, 107798142804281290451059200, 4441362930723337358985334172160, 398854836980938754158182857661404160, 77576833096847783279235708819073596288000
Offset: 0

Views

Author

Juan Arias-de-Reyna, Jun 06 2017

Keywords

Comments

These numbers determine the half moments of the Rvachëv function. The Rvachëv function is related to the Fabius function, up(x)=F(x+1) for |x|<1 and up(x)=0 for |x|>=1.

Crossrefs

Programs

  • Mathematica
    d[0] = 1;
    d[n_] := d[n] =
      Sum[Binomial[n + 1, k] d[k], {k, 0, n - 1}]/((n + 1)*(2^n - 1));
    a[n_] := (n + 1)! Product[(2^k - 1), {k, 1, n}] d[n];
    Table[a[n], {n, 0, 14}]

Formula

a(n) = (n+1)!*Product_{k=1..n}(2^k-1)*d(n) where d(n) are the rationals defined by the recurrence d(0)=1; d(n)=Sum_{k=0..n-1}[binomial(n+1,k)d(k)]/((n+1)*(2^n-1)) (cf. A288161).
Showing 1-4 of 4 results.