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.

Previous Showing 11-15 of 15 results.

A143228 Triangle read by rows, T(n,k) = p(n) * p(k), where p(n) = the number of partitions of n, for 0 <= k <= n.

Original entry on oeis.org

1, 1, 1, 2, 2, 4, 3, 3, 6, 9, 5, 5, 10, 15, 25, 7, 7, 14, 21, 35, 49, 11, 11, 22, 33, 55, 77, 121, 15, 15, 30, 45, 75, 105, 165, 225, 22, 22, 44, 66, 110, 154, 242, 330, 484, 30, 30, 60, 90, 150, 210, 330, 450, 660, 900, 42, 42, 84, 126, 210, 294, 462, 630, 924, 1260, 1764
Offset: 0

Views

Author

Gary W. Adamson, Jul 31 2008

Keywords

Examples

			First few rows of the triangle:
   1;
   1,  1;
   2,  2,  4;
   3,  3,  6,  9;
   5,  5, 10, 15, 25;
   7,  7, 14, 21, 35,  49;
  11, 11, 22, 33, 55,  77, 121;
  15, 15, 30, 45, 75, 105, 165, 225;
  ...
T(7,4) = 75 = p(7) * p(4) = 15 * 5.
		

Crossrefs

Cf. A000041, A143229 (row sums).
Main diagonal gives: A001255.

Programs

  • Magma
    A143228:= func< n,k | NumberOfPartitions(n)*NumberOfPartitions(k) >;
    [A143228(n,k): k in [0..n], n in [0..12]]; // G. C. Greubel, Aug 27 2024
    
  • Mathematica
    Table[PartitionsP[n]*PartitionsP[k], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Aug 27 2024 *)
  • SageMath
    def A143215(n,k): return number_of_partitions(n)*number_of_partitions(k)
    flatten([[A143215(n,k) for k in range(n+1)] for n in range(13)]) # G. C. Greubel, Aug 27 2024

Formula

T(n, 0) = A000041(n) (left border).
Sum_{k=0..n} T(n, k) = A143229(n) (row sums).
Sum_{k=0..n} (-1)^k*T(n, k) = (-1)^n*A000041(n)*A087787(n). - G. C. Greubel, Aug 27 2024

A182722 a(n) = A005291(n+1)-A182712(n).

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 3, 5, 10, 14, 26, 36, 60, 83, 128, 175, 261, 351, 504, 674, 943, 1247, 1711, 2243
Offset: 0

Views

Author

Omar E. Pol, Nov 28 2010, Nov 29 2010

Keywords

Comments

The difference between two apparently unrelated sequences which happen to have the same initial terms. - N. J. A. Sloane, Dec 01 2010

Crossrefs

Formula

a(n) = A005291(n+1)-A182712(n)

A277963 G.f.: 1/(1+x) * Product_{k>=1} 1/(1-x^k)^k.

Original entry on oeis.org

1, 0, 3, 3, 10, 14, 34, 52, 108, 174, 326, 533, 946, 1539, 2628, 4251, 7046, 11288, 18313, 29017, 46261, 72533, 113942, 176841, 274353, 421680, 647065, 985593, 1497641, 2261971, 3406992, 5105317, 7628112, 11346861, 16829094, 24861952, 36623009, 53756775
Offset: 0

Views

Author

Vaclav Kotesovec, Nov 06 2016

Keywords

Comments

Convolution of A000219 and A033999.

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[1/(1+x)*Product[1/(1-x^k)^k, {k, 1, 50}], {x, 0, 50}], x]

Formula

a(n) = Sum_{k=0..n} (-1)^(n-k)*A000219(k).
a(n) ~ Zeta(3)^(7/36) * exp(3 * Zeta(3)^(1/3) * (n/2)^(2/3) + 1/12) / (A * sqrt(3*Pi) * 2^(47/36) * n^(25/36)), where A = A074962 is the Glaisher-Kinkelin constant.

A293464 a(n) = Sum_{k=0..n} (-1)^k * 2^k * p(k), where p(k) is the partition function A000041.

Original entry on oeis.org

1, -1, 7, -17, 63, -161, 543, -1377, 4255, -11105, 31903, -82785, 232607, -594785, 1617055, -4150113, 10988703, -27939681, 72985759, -183915361, 473541791, -1187402593, 3015290015, -7512413025, 18911702175, -46787875681, 116689317023, -287306044257
Offset: 0

Views

Author

Vaclav Kotesovec, Oct 09 2017

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Sum[(-1)^k * 2^k * PartitionsP[k], {k, 0, n}], {n, 0, 30}]

Formula

a(n) ~ (-1)^n * 2^(n-1) * exp(Pi*sqrt(2*n/3)) / (3^(3/2)*n).
a(n) ~ (-1)^n * 2/3 * 2^n * A000041(n).

A195308 a(n) = A005291(n) + A005291(n+1).

Original entry on oeis.org

1, 1, 1, 2, 3, 5, 7, 11, 15, 22, 30, 43, 58, 81, 109, 150, 200, 271, 359, 481, 633, 838, 1095, 1438, 1867, 2430, 3136, 4053, 5200, 6676, 8519, 10871, 13802, 17514, 22129, 27940, 35141, 44155, 55299, 69179, 86286, 107495, 133562, 165744, 205188, 253691, 312975, 385619
Offset: 1

Views

Author

Omar E. Pol, Feb 03 2012

Keywords

Comments

This sequence arises from A005291 in the same way as A000041 arises from A182712.
Observation: a(3)..a(13) coincide with a sequence related to Stirling's numbers from the Jordan's book.

References

  • Charles Jordan, Calculus of finite differences, Chelsea Publishing Co., 1965, chapter IV, pp. 153-155.

Crossrefs

Formula

a(n) = A000041(n-2), 2 <= n <= 11. - Omar E. Pol, Feb 24 2013

Extensions

More terms from Amiram Eldar, May 17 2025
Previous Showing 11-15 of 15 results.