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.

A082405 a(n) = 34*a(n-1) - a(n-2); a(0)=0, a(1)=6.

Original entry on oeis.org

0, 6, 204, 6930, 235416, 7997214, 271669860, 9228778026, 313506783024, 10650001844790, 361786555939836, 12290092900109634, 417501372047787720, 14182756556724672846, 481796221556591089044, 16366888776367372354650
Offset: 0

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Author

Lekraj Beedassy, Apr 23 2003

Keywords

Comments

Sequence refers to inradius of primitive Pythagorean triangle with consecutive legs, even followed by odd. It has semiperimeter A046176(n+1) and area a(n)*A046176(n+1).

Crossrefs

Cf. A046176.

Programs

  • Mathematica
    a[0] = 1; a[1] = 6; a[n_] := 34 a[n-1] - a[n-2]; Table[a[n], {n,0,15}] (* or *) LinearRecurrence[{34,-1}, {1,6}, 16] (* Indranil Ghosh, Feb 18 2017 *)

Formula

For n > 1, a(n)/2 = A001652(2*n-1) - Sum_{k=0..n-1} A001333(4*k); e.g., 6930/2 = 4059 - (17+577). - Charlie Marion, Jul 31 2003
a(n) = A001109(2n).
G.f.: 6*x/(1 - 34*x + x^2). - Philippe Deléham, Nov 18 2008
a(n) = 6*A029547(n-1). - R. J. Mathar, Jun 07 2016