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.

A141417 (-1)^(n+1)*A091137(n)*a(0,n), where a(i,j) = Integral_{x=i..i+1} x*(x-1)*(x-2)*...*(x-j+1)/j! dx.

Original entry on oeis.org

-1, 1, 1, 1, 19, 27, 863, 1375, 33953, 57281, 3250433, 5675265, 13695779093, 24466579093, 132282840127, 240208245823, 111956703448001, 205804074290625, 151711881512390095, 281550972898020815, 86560056264289860203, 161867055619224199787, 20953816286242674495191, 39427936010479474495191
Offset: 0

Views

Author

Paul Curtz, Aug 05 2008

Keywords

Comments

This is row i=0 of an array defined as T(i,j) = (-1)^(i+j+1)*A091137(j)*a(i,j), columns j >= 0, which starts
-1, 1, 1, 1, 19, 27, 863, ...
1, -3, 5, 1, 11, 11, 271, ...
-1, 5, -23, 9, 19, 11, 191, ...
1, -7, 53, -55, 251, 27, 271, ...
-1, 9, -95, 161, -1901, 475, 863, ...
1, -11, 149, -351, 6731, -4277, 19087, ...
...
The first two rows are related via T(0,j) = A027760(j)*T(0,j-1) - T(1,j).

References

  • P. Curtz, Integration .., note 12, C.C.S.A., Arcueil, 1969.

Crossrefs

Programs

  • Maple
    A091137 := proc(n) local a, i, p ; a := 1 ; for i from 1 do p := ithprime(i) ; if p > n+1 then break; fi; a := a*p^floor(n/(p-1)) ; od: a ; end proc:
    A048994 := proc(n, k) combinat[stirling1](n, k) ; end proc:
    a := proc(i,j) add(A048994(j,k)*x^k,k=0..j) ; int(%,x=i..i+1) ; %/j! ; end proc:
    A141417 := proc(n) (-1)^(n+1)*A091137(n)*a(0,n) ; end proc:
    seq(A141417(n),n=0..40) ; # R. J. Mathar, Nov 17 2010
  • Mathematica
    (* a7 = A091137 *) a7[n_] := a7[n] = Times @@ Select[ Divisors[n]+1, PrimeQ]*a7[n-1]; a7[0]=1; a[n_] := (-1)^(n+1) * a7[n] * Integrate[ (-1)^n*Pochhammer[-x, n], {x, 0, 1}]/n!; Table[a[n], {n, 0, 10}] (* Jean-François Alcover, Aug 10 2012 *)
  • Maxima
    a(n):=if n=0 then -1 else num(n*(n+1)*sum(((-1)^(n-k)*stirling2(n+k,k)*binomial(2*n-1,n-k))/((n+k)*(n+k-1)),k,1,n)); /* Vladimir Kruchinin, Dec 12 2016 */

Formula

a(i,j) = a(i-1,j) + a(i-1,j-1), see reference page 33.
(q+1-j)*Sum_{j=0..q} a(i,j)*(-1)^(q-j) = binomial(i,q), see reference page 35.
a(n) = numerator(n*(n+1)*Sum_{k=1..n} ((-1)^(n-k)*Stirling2(n+k,k)*binomial(2*n-1,n-k))/((n+k)*(n+k-1))), n>0, a(0)=-1. - Vladimir Kruchinin, Dec 12 2016

Extensions

Erroneous formula linking A091137 and A002196 removed, and more terms and program added by R. J. Mathar, Nov 17 2010

A141530 a(n) = 4*n^3 - 6*n^2 + 1.

Original entry on oeis.org

1, -1, 9, 55, 161, 351, 649, 1079, 1665, 2431, 3401, 4599, 6049, 7775, 9801, 12151, 14849, 17919, 21385, 25271, 29601, 34399, 39689, 45495, 51841, 58751, 66249, 74359, 83105, 92511, 102601, 113399, 124929, 137215, 150281, 164151, 178849, 194399, 210825, 228151
Offset: 0

Views

Author

Paul Curtz, Aug 12 2008

Keywords

Crossrefs

See Librandi's comment in A078371.

Programs

Formula

a(n) = (2*n-1)*(2*n^2 - 2*n - 1) = A060747(n)*A132209(n-1), n > 1. - R. J. Mathar, Feb 22 2009
G.f.: (1 - 5*x + 19*x^2 + 9*x^3)/(1-x)^4. - Jaume Oliver Lafont, Aug 30 2009
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) with a(0)=1, a(1)=-1, a(2)=9, a(3)=55. - Harvey P. Dale, Nov 30 2011
E.g.f.: (1 - 2*x + 6*x^2 + 4*x^3)*exp(x). - G. C. Greubel, Mar 29 2021

Extensions

Corrected, completed and edited, following an observation from Vincenzo Librandi, by M. F. Hasler, Feb 12 2009
Further edited by N. J. A. Sloane, Feb 13 2009

A165313 Triangle T(n,k) = A091137(k-1) read by rows.

Original entry on oeis.org

1, 1, 2, 1, 2, 12, 1, 2, 12, 24, 1, 2, 12, 24, 720, 1, 2, 12, 24, 720, 1440, 1, 2, 12, 24, 720, 1440, 60480, 1, 2, 12, 24, 720, 1440, 60480, 120960, 1, 2, 12, 24, 720, 1440, 60480, 120960, 3628800, 1, 2, 12, 24, 720, 1440, 60480, 120960, 3628800, 7257600, 1, 2, 12
Offset: 1

Views

Author

Paul Curtz, Sep 14 2009

Keywords

Comments

From a study of modified initialization formulas in Adams-Bashforth (1855-1883) multisteps method for numerical integration. On p.36, a(i,j) comes from (j!)*a(i,j) = Integral_{u=i,..,i+1} u*(u-1)*...*(u-j+1) du; see p.32.
Then, with i vertical, j horizontal, with unreduced fractions, partial array is:
0) 1, 1/2, -1/12, 1/24, -19/720, 27/1440, ... = 1/log(2)
1) 1, 3/2, 5/12, -1/24, 11/720, -11/1440, ... = 2/log(2)
2) 1, 5/2, 23/12, 9/24, -19/720, 11/1440, ... = 4/log(2)
3) 1, 7/2, 53/12, 55/24, 251/720, -27/1440, ... = 8/log(2)
4) 1, 9/2, 95/12, 161/24, 1901/720, 475/1440, ... = 16/log(2)
5) 1, 11/2, 149/12, 351/24, 6731/720, 4277/1440, ... = 32/log(2)
... [improved by Paul Curtz, Jul 13 2019]
First line: the reduced terms are A002206/A002207, logarithmic or Gregory numbers G(n). The difference between the second line and the first one is 0 together A002206/A002207. This is valid for the next lines. - Paul Curtz, Jul 13 2019
See A141417, A140825, A157982, horizontal numerators: A141047, vertical numerators: A000012, A005408, A140811, A141530, A157411. On p.56, coefficients are s(i,q) = (1/q!)* Integral_{u=-i-1,..,1} u*(u+1)*...*(u+q-1) du.
Unreduced fractions array is:
-1) 1, 1/2, 5/12, 9/24, 251/720, 475/1440, ... = A002657/A091137
0) 2, 0/2, 4/12, 8/24, 232/720, 448/1440, ... = A195287/A091137
1) 3, -3/2, 9/12, 9/24, 243/720, 459/1440, ...
2) 4, -8/2, 32/12, 0/24, 224/720, 448/1440, ...
3) 5, -15/2, 85/12, -55/24, 475/720, 475/1440, ...
...
(on p.56 up to 6)). See A147998. Vertical numerators: A000027, A147998, A152064, A157371, A165281.
From Paul Curtz, Jul 14 2019: (Start)
Difference table from the second line and the first one difference:
1, -1/2, -1/12, -1/24, -19/720, -27/1440, ...
-3/2, 5/12, 1/24, 11/720, 11/1440, ...
23/12, -9/24, -19/720, -11/1440, ...
-55/24, 251/720, 27/1440, ...
1901/720, -475/1440,
-4277/1440, ...
...
Compare the lines to those of the first array.
The verticals are the signed diagonals of the first array. (End)

Examples

			1;
1,2;
1,2,12;
1,2,12,24;
1,2,12,24,720;
		

References

  • P. Curtz, Intégration numérique des systèmes différentiels à conditions initiales, Centre de Calcul Scientifique de l'Armement, Note 12, Arcueil, 1969.

Crossrefs

Programs

  • Mathematica
    (* a = A091137 *) a[n_] := a[n] = Product[d, {d, Select[Divisors[n]+1, PrimeQ]}]*a[n-1]; a[0]=1; Table[Table[a[k-1], {k, 1, n}], {n, 1, 11}] // Flatten (* Jean-François Alcover, Dec 18 2014 *)
Showing 1-3 of 3 results.