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.

A081864 Sum of 5th powers of the divisors of odd numbers: a(n) = sigma_5(2n-1).

Original entry on oeis.org

1, 244, 3126, 16808, 59293, 161052, 371294, 762744, 1419858, 2476100, 4101152, 6436344, 9768751, 14408200, 20511150, 28629152, 39296688, 52541808, 69343958, 90595736, 115856202, 147008444, 185349918, 229345008, 282492057, 346445352, 418195494, 503448552, 604168400
Offset: 1

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Author

N. J. A. Sloane. This sequence was in the 1973 "Handbook", but then was deleted from the database because of confusion with A002594. Resubmitted by Benoit Cloitre, Apr 12 2003. Entry revised by N. J. A. Sloane, Jun 10 2012

Keywords

References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

Crossrefs

Programs

  • Magma
    [DivisorSigma(5,2*n-1):n in [1..30]]; // Marius A. Burtea, Aug 17 2019
  • Maple
    with(numtheory); [seq(sigma[5](2*n-1),n=1..100)];
  • Mathematica
    DivisorSigma[5,Range[1,61,2]] (* Harvey P. Dale, Jan 12 2016 *)
  • PARI
    a(n) = sigma(2*n-1, 5); \\ Michel Marcus, Aug 17 2019
    

Formula

Sum_{k=1..n} a(k) ~ c * n^6, where c = Pi^6 / 180 = 5.341051... = 3*A333972. - Amiram Eldar, Jan 08 2025

Extensions

Definition clarified by Harvey P. Dale, Jan 12 2016

A265021 Sum of fifth powers of the first n even numbers.

Original entry on oeis.org

0, 32, 1056, 8832, 41600, 141600, 390432, 928256, 1976832, 3866400, 7066400, 12220032, 20182656, 32064032, 49274400, 73574400, 107128832, 152564256, 213030432, 292265600, 394665600, 525356832, 690273056, 896236032, 1151040000, 1463540000, 1843744032
Offset: 0

Views

Author

Assoul Abdelkarim, Nov 30 2015

Keywords

Examples

			a(4) =  2^5 + 4^5 + 6^5 + 8^5 = 41600.
		

Crossrefs

Cf. A000539, A002594 (the same for odd numbers).

Programs

  • Magma
    [(8/3)*n^2*(n+1)^2*(2*n^2+2*n-1): n in [0..30]]; // Vincenzo Librandi, Dec 01 2015
    
  • Mathematica
    Accumulate[Range[0, 60, 2]^5] (* Michael De Vlieger, Nov 30 2015 *)
    CoefficientList[Series[32 x (1 + 26 x + 66 x^2 + 26 x^3 + x^4)/(1 - x)^7, {x, 0, 33}], x] (* Vincenzo Librandi, Dec 01 2015 *)
  • PARI
    vector(100, n, n--; (8/3)*n^2*(n+1)^2*(2*n^2+2*n-1)) \\ Altug Alkan, Dec 01 2015

Formula

a(n) = 32 * Sum_{i=0..n} i^5 = (8/3)*n^2*(n+1)^2*(2*n^2+2*n-1).
a(n) = 32 * A000539(n).
G.f.: 32*x*(1 + 26*x + 66*x^2 + 26*x^3 + x^4)/(1-x)^7. - Vincenzo Librandi, Dec 01 2015
a(n) = 7*a(n-1)-21*a(n-2)+35*a(n-3)-35*a(n-4)+21*a(n-5)-7*a(n-6)+a(n-7). - Vincenzo Librandi, Dec 01 2015

A349490 Sum of the n-th powers of the first n odd numbers.

Original entry on oeis.org

1, 10, 153, 3108, 79225, 2437006, 87922513, 3642188936, 170423429841, 8891285549650, 511800291063721, 32222868466588460, 2202868653419747209, 162509566498902542934, 12868118600594014094625, 1088626666242258867384848, 97994054039441765759931169
Offset: 1

Views

Author

Seiichi Manyama, Dec 09 2021

Keywords

Crossrefs

Sum of the k-th powers of the first n odd numbers: A000290 (k=1), A000447 (k=2), A002593 (k=3), A002309 (k=4), A002594 (k=5), A259322 (k=6).

Programs

  • Mathematica
    Table[Sum[(2*k-1)^n, {k,1,n}], {n,1,20}] (* Vaclav Kotesovec, Dec 09 2021 *)
  • PARI
    a(n) = sum(k=1, n, (2*k-1)^n);

Formula

a(n) = Sum_{k=1..n} (2*k-1)^n.
a(n) ~ 2^n * n^n / (exp(1/2) - exp(-1/2)). - Vaclav Kotesovec, Dec 09 2021
Showing 1-3 of 3 results.