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 1-2 of 2 results.

A193546 Numerator of the third row of the inverse Akiyama-Tanigawa algorithm from 1/n.

Original entry on oeis.org

1, 1, 7, 17, 41, 731, 8563, 27719, 190073, 516149, 1013143139, 1519024289, 14108351869, 14399405173, 23142912688967, 83945247395407, 84894728616107, 3204549982389941, 262488267575333123, 9027726081126601799, 2026692221793223022131, 1375035304877251309001
Offset: 0

Views

Author

Paul Curtz, Aug 27 2011

Keywords

Comments

Akiyama-Tanigawa from 1/n gives Bernoulli A164555(n)/A027642(n).
Reciprocally
1, 1/2, 5/12, 3/8, 251/720, 95/288, 19087/60480, 5257/17280,
1/2, 1/6, 1/8, 19/180, 3/32, 863/10080, 275/3456,
1/3, 1/12, 7/120, 17/360, 41/1008, 731/20160, 8563/259200,
1/4, 1/20, 1/30, 11/420, 89/4032,5849/302400,
1/5, 1/30, 3/140, 83/5040, 59/4320,
1/6, 1/42, 5/336,
1/7, 1/56,
1/8.
First row: A002208/A002209 or reduced A002657(n)/A091137(n) unsigned.
Second row: A002206(n+1)/A002689(n) unsigned. See A141417(n) and A174727(n).
Third row: a(n)/A194506(n).

Crossrefs

Cf. A194506 (denominator).

Programs

  • Maple
    read("transforms3") ;
    L := [seq(1/n,n=1..20)] ;
    L1 := AKIYAMATANIGAWAi(L) ;
    L2 := AKIYATANI(L1) ;
    L3 := AKIYATANI(L2) ;
    apply(numer,%) ; # R. J. Mathar, Aug 27 2011
    # second Maple program:
    b:= proc (n, k) option remember;
          `if`(n=0, 1/(k+1), b(n-1, k) -b(n-1, k+1)/n)
        end:
    a:= n-> numer(b(n, 2)):
    seq(a(n), n=0..30);  # Alois P. Heinz, Aug 27 2011
  • Mathematica
    a[n_, 0] := 1/(n+1); a[n_, m_] := a[n, m] = a[n, m-1] - a[n+1, m-1]/m; Table[a[2, m], {m, 0, 21}] // Numerator (* Jean-François Alcover, Aug 09 2012 *)
    Numerator@Table[(-1)^n (n + 1) Integrate[FunctionExpand[x Binomial[x, n + 1]], {x, 0, 1}], {n, 0, 20}] (* Vladimir Reshetnikov, Feb 01 2017 *)

Formula

a(n)/A194506(n) = (-1)^n * (n+1) * Integral_{0Vladimir Reshetnikov, Feb 01 2017

A321943 Decimal expansion of Ni_1 = (1/2)*(gamma - log(2*Pi)) + 1, where gamma is Euler's constant (or the Euler-Mascheroni constant).

Original entry on oeis.org

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

Views

Author

Stefano Spezia, Dec 12 2018

Keywords

Comments

This constant links Euler's constant and Pi to the values of the Riemann zeta function at positive integers (see formulas).

Examples

			0.369669299246093688522926308635583575659682194332178386585...
		

References

  • D. Suryanarayana, Sums of Riemann zeta function, Math. Student, 42 (1974), 141-143.

Crossrefs

Cf. A001620 (Euler's constant), A000796 (Pi).

Programs

  • Maple
    Digits := 100; evalf((1/2)*(gamma-ln(2*Pi))+1);
  • Mathematica
    First[RealDigits[N[(1/2)*(EulerGamma-Log[2*Pi])+1, 100], 10]]
  • PARI
    (1/2)*(Euler-log(2*Pi))+1
    
  • Python
    from mpmath import *
    mp.dps = 100; mp.pretty = True
    +(1/2)*(euler-log(2*pi))+1

Formula

Ni_1 = Sum_{k>=2} (-1)^k*zeta(k)/(k+1).
Ni_1 = Sum_{n>0} (Integral_{x=0..1} x^2*(1-x)_{n-1} dx)/(n*n!), where (z)_n = z*(z+1)*(z+2)*...*(z+n-1) is the Pochhammer symbol.
Ni_1 = Sum_{n>=0} A193546(n)/(A000290(n + 1)*A194506(n)).
Showing 1-2 of 2 results.