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 1-3 of 3 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

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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

A232853 Repeat n+1 times A091137(n).

Original entry on oeis.org

1, 2, 2, 12, 12, 12, 24, 24, 24, 24, 720, 720, 720, 720, 720, 1440, 1440, 1440, 1440, 1440, 1440, 60480, 60480, 60480, 60480, 60480, 60480, 60480, 120960, 120960, 120960, 120960, 120960, 120960, 120960, 120960, 3628800
Offset: 0

Views

Author

Paul Curtz, Dec 01 2013

Keywords

Comments

A002657(n) and A091137(n) are linked to the Bernoulli numbers B n.
Unreduced differences table of A002657(n)/A091137(n):
1, 1/2, 5/12, 9/24, 251/720, 475/1440,...
-1/2, -1/12, -1/24, -19/720, -27/1440,... =-A141417(n+1)/A091137(n+1),
5/12, 1/24, 11/720, 11/1440,...
-9/24, -19/720, -11/1440,...
251/720, 27/1440,...
-475/1440,... etc.
This is an autosequence of the second kind: its inverse binomial transform is the signed sequence with the main diagonal double of the first upper diagonal.
a(n) is the denominators written by antidiagonals.

Examples

			1,
2,   2,
12, 12, 12,
24, 24, 24, 24, etc.
		

References

  • P. Curtz, Intégration numérique des systèmes différentiels à conditions initiales. Centre de Calcul Scientifique de l'Armement, Arcueil 1969. Pages 36 and 56.

Crossrefs

Cf. A195287, A002208/A002209 (reduced autosequence), A193546, A174727, A165313.

Formula

Repeat n+1 times A091137(n). Triangle.

A176493 A091137(n)/(n+1).

Original entry on oeis.org

1, 1, 4, 6, 144, 240, 8640, 15120, 403200, 725760, 43545600, 79833600, 201180672000, 373621248000, 2092278988800, 3923023104000, 1883051089920000, 3556874280960000, 2688996956405760000, 5109094217170944000, 1605715325396582400000, 3065456530302566400000
Offset: 0

Views

Author

Paul Curtz, Apr 19 2010

Keywords

Formula

a(n) = A174727(n)/A027760(n+1).
Showing 1-3 of 3 results.