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.

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A220944 Expansion of (1+3*x+5*x^2-x^3)/((1-x^2)*(1-3*x^2)).

Original entry on oeis.org

1, 3, 9, 11, 33, 35, 105, 107, 321, 323, 969, 971, 2913, 2915, 8745, 8747, 26241, 26243, 78729, 78731, 236193, 236195, 708585, 708587, 2125761, 2125763, 6377289, 6377291, 19131873, 19131875, 57395625, 57395627, 172186881, 172186883, 516560649, 516560651
Offset: 0

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Author

Philippe Deléham, Apr 13 2013

Keywords

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{0, 4, 0, -3}, {1, 3, 9, 11}, 40] (* T. D. Noe, Apr 17 2013 *)

Formula

a(n) = a(n-1)+2 if n odd.
a(n) = a(n-1)*3 if n even.
a(2n) = 4*3^n-3 = A036543(n), a(2n+1) = 4*3^n-1 = A171498(n).
a(n) = 4*a(n-2) - 3*a(n-4) with a(0)=1, a(1)=3, a(2)=9, a(3)=11.

A238207 Square array T(n,k), n>=0, k>=0, read by antidiagonals, where T(0,k) is A032766(k) and T(n,k) = 3*T(n-1,k) + 2 for n>0.

Original entry on oeis.org

0, 1, 2, 3, 5, 8, 4, 11, 17, 26, 6, 14, 35, 53, 80, 7, 20, 44, 107, 161, 242, 9, 23, 62, 134, 323, 485, 728, 10, 29, 71, 188, 404, 971, 1457, 2186, 12, 32, 89, 215, 566, 1214, 2915, 4373, 6560, 13, 28, 98, 269, 647, 1700, 3644, 8747, 13121, 19682, 15, 41, 116
Offset: 0

Views

Author

Philippe Deléham, Feb 20 2014

Keywords

Comments

Permutation of nonnegative integers.

Examples

			Square array begins:
0, 1, 3, 4, 6, 7, 9, 10, ...
2, 5, 11, 14, 20, 23, 29, 32, ...
8, 17, 35, 44, 62, 71, 89, 98, ...
26, 53, 107, 134, 188, 215, 269, 296, ...
80, 161, 323, 404, 566, 647, 809, 890, ...
242, 485, 971, 1214, 1700, 1943, 2429, 2672, ...
728, 1457, 2915, 3644, 5102, 5831, 7289, 8018, ...
2186, 4373, 8747, 10934, 15308, 17495, 21869, 24056, ...
...
		

Crossrefs

Formula

T(n,k) = T(0,k)*3^n + T(n,0) where T(0,k) = A032766(k) and T(n,0) = 3^n - 1 = A024023(n).
Previous Showing 11-12 of 12 results.