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.

A006974 Coefficients of Chebyshev T polynomials: a(n) = A053120(n+8, n), n >= 0.

Original entry on oeis.org

1, 9, 50, 220, 840, 2912, 9408, 28800, 84480, 239360, 658944, 1770496, 4659200, 12042240, 30638080, 76873728, 190513152, 466944000, 1133117440, 2724986880, 6499598336, 15386804224, 36175872000, 84515225600, 196293427200, 453437816832
Offset: 0

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Comments

If X_1,X_2,...,X_n are 2-blocks of a (2n+1)-set X then, for n>=3, a(n-3) is the number of (n+4)-subsets of X intersecting each X_i, (i=1,2,...,n). - Milan Janjic, Nov 18 2007
The fourth corrector line for transforming 2^n offset 0 with a leading 1 into the Fibonacci sequence. [Al Hakanson (hawkuu(AT)gmail.com), Jun 01 2009]

References

  • M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 795.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A039991 (see column 8), A003472 (partial sums), A053120.

Programs

  • Magma
    [2^(n-1)/4*Binomial(n+3,3)*(n+8) : n in [0..25]]; // Brad Clardy, Mar 08 2012
  • Maple
    a := n->n*(n+1)*(n+2)*(n+7)*2^(n-5)/3;

Formula

G.f.: (1-x)/(1-2*x)^5.
a(n) = Sum_{k=0..floor((n+8)/2)} C(n+8, 2k)*C(k, 4). - Paul Barry, May 15 2003
Binomial transform of a(n)=(24*n^4-134*n^3+261*n^2-130*n+3)/3 offset 0. a(3)=220. [Al Hakanson (hawkuu(AT)gmail.com), Jun 01 2009]
a(n) = 2^(n-3)*binomial(n+3, 3)*(n+8). - Brad Clardy, Mar 08 2012 [See a comment in A053120 on subdiagonals. - Wolfdieter Lang, Jan 03 2020]
E.g.f.: (1/3)*exp(2*x)*(3 + 21*x + 27*x^2 + 10*x^3 + x^4). - Stefano Spezia, Aug 17 2019

Extensions

Name clarified by Wolfdieter Lang, Nov 26 2019