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.

A255961 Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is Euler transform of (j->j*k).

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 3, 0, 1, 3, 7, 6, 0, 1, 4, 12, 18, 13, 0, 1, 5, 18, 37, 47, 24, 0, 1, 6, 25, 64, 111, 110, 48, 0, 1, 7, 33, 100, 215, 303, 258, 86, 0, 1, 8, 42, 146, 370, 660, 804, 568, 160, 0, 1, 9, 52, 203, 588, 1251, 1938, 2022, 1237, 282, 0
Offset: 0

Views

Author

Alois P. Heinz, Mar 11 2015

Keywords

Comments

A(n,k) is the number of partitions of n when parts i are of k*i kinds. A(2,2) = 7: [2a], [2b], [2c], [2d], [1a,1a], [1a,1b], [1b,1b].

Examples

			Square array A(n,k) begins:
  1,  1,   1,    1,    1,     1,     1,     1, ...
  0,  1,   2,    3,    4,     5,     6,     7, ...
  0,  3,   7,   12,   18,    25,    33,    42, ...
  0,  6,  18,   37,   64,   100,   146,   203, ...
  0, 13,  47,  111,  215,   370,   588,   882, ...
  0, 24, 110,  303,  660,  1251,  2160,  3486, ...
  0, 48, 258,  804, 1938,  4005,  7459, 12880, ...
  0, 86, 568, 2022, 5400, 12150, 24354, 44885, ...
		

Crossrefs

Rows n=0-3 give: A000012, A001477, A055998, A101853.
Main diagonal gives A255672.
Antidiagonal sums give A299166.

Programs

  • Maple
    A:= proc(n, k) option remember; `if`(n=0, 1, k*add(
          A(n-j, k)*numtheory[sigma][2](j), j=1..n)/n)
        end:
    seq(seq(A(n, d-n), n=0..d), d=0..12);
  • Mathematica
    A[n_, k_] := A[n, k] = If[n==0, 1, k*Sum[A[n-j, k]*DivisorSigma[2, j], {j, 1, n}]/n]; Table[Table[A[n, d-n], {n, 0, d}], {d, 0, 12}] // Flatten (* Jean-François Alcover, Feb 02 2016, after Alois P. Heinz *)

Formula

G.f. of column k: Product_{j>=1} 1/(1-x^j)^(j*k).
T(n,k) = Sum_{i=0..k} C(k,i) * A257673(n,k-i).

A101854 a(n) = n*(n+1)*(n^2 + 21*n + 50)/24.

Original entry on oeis.org

6, 24, 61, 125, 225, 371, 574, 846, 1200, 1650, 2211, 2899, 3731, 4725, 5900, 7276, 8874, 10716, 12825, 15225, 17941, 20999, 24426, 28250, 32500, 37206, 42399, 48111, 54375, 61225, 68696, 76824, 85646, 95200, 105525, 116661, 128649, 141531, 155350
Offset: 1

Views

Author

Cecilia Rossiter (cecilia(AT)noticingnumbers.net), Dec 18 2004

Keywords

Comments

5th partial summation within series as series accumulate n times from an initial sequence of Euler Triangle's row 3: 1,4,1.

Crossrefs

5th row of the array shown in A101853.
Partial sums of A101853.

Programs

  • Mathematica
    Table[25 n/12+(71n^2)/24+(11n^3)/12+n^4/24,{n,40}] (* or *) LinearRecurrence[{5,-10,10,-5,1},{6,24,61,125,225},40] (* Harvey P. Dale, Nov 05 2011 *)

Formula

G.f.: x*(6 - 6*x + x^2)/(1-x)^5. - Maksym Voznyy (voznyy(AT)mail.ru), Aug 11 2009; checked and corrected by R. J. Mathar, Sep 16 2009
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5), n > 5. - Harvey P. Dale, Nov 05 2011
E.g.f.: exp(x)*x*(144 + 144*x + 28*x^2 + x^3)/24. - Stefano Spezia, Oct 14 2022

Extensions

Formula moved to be the definition by Eric M. Schmidt, Dec 12 2013

A101855 a(n) = n*(n+1)*(n+2)*(n+4)*(n+23)/120.

Original entry on oeis.org

6, 30, 91, 216, 441, 812, 1386, 2232, 3432, 5082, 7293, 10192, 13923, 18648, 24548, 31824, 40698, 51414, 64239, 79464, 97405, 118404, 142830, 171080, 203580, 240786, 283185, 331296, 385671, 446896, 515592, 592416, 678062, 773262, 878787, 995448
Offset: 1

Views

Author

Cecilia Rossiter (cecilia(AT)noticingnumbers.net), Dec 18 2004

Keywords

Comments

6th partial summation within series as series accumulate n times from an initial sequence of Euler Triangle's row 3: 1,4,1. 6th row of the array shown in A101853. Partial sums of A101854.

Programs

  • Mathematica
    Table[n(n+1)(n+2)(n+4)(n+23)/120,{n,40}] (* or *) LinearRecurrence[ {6,-15,20,-15,6,-1},{6,30,91,216,441,812},40](* Harvey P. Dale, Feb 07 2013 *)

Formula

G.f.: x*(6-6*x+x^2) / (x-1)^6. - R. J. Mathar, Dec 06 2011
a(1)=6, a(2)=30, a(3)=91, a(4)=216, a(5)=441, a(6)=812, a(n)=6*a(n-1)- 15*a(n-2)+ 20*a(n-3)-15*a(n-4)+6*a(n-5)-a(n-6). - Harvey P. Dale, Feb 07 2013
Showing 1-3 of 3 results.