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 11-13 of 13 results.

A357238 Inverse Moebius transform of tribonacci numbers (A000073).

Original entry on oeis.org

0, 1, 1, 3, 4, 9, 13, 27, 45, 86, 149, 285, 504, 941, 1710, 3163, 5768, 10662, 19513, 35978, 66026, 121565, 223317, 411053, 755480, 1390042, 2555802, 4701713, 8646064, 15904390, 29249425, 53801243, 98950246, 182003370, 334745794, 615704412, 1132436852, 2082895617, 3831006934
Offset: 1

Views

Author

Ilya Gutkovskiy, Sep 19 2022

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 39; CoefficientList[Series[Sum[x^(2 k)/(1 - x^k - x^(2 k) - x^(3 k)), {k, 1, nmax}], {x, 0, nmax}], x] // Rest
  • PARI
    f(n) = ([0, 1, 0; 0, 0, 1; 1, 1, 1]^n)[1, 3]; \\ A000073
    a(n) = sumdiv(n, d, f(d)); \\ Michel Marcus, Sep 20 2022

Formula

G.f.: Sum_{k>=1} x^(2*k) / (1 - x^k - x^(2*k) - x^(3*k)).
G.f.: Sum_{k>=1} A000073(k) * x^k / (1 - x^k).
a(n) = Sum_{d|n} A000073(d).

A357239 Inverse Moebius transform of tetranacci number (A000078).

Original entry on oeis.org

0, 0, 1, 1, 2, 5, 8, 16, 30, 58, 108, 214, 401, 781, 1493, 2888, 5536, 10705, 20569, 39707, 76433, 147420, 283953, 547566, 1055028, 2034029, 3919974, 7556717, 14564533, 28075593, 54114452, 104311848, 201062094, 387564973, 747044844, 1439986130, 2775641472, 5350241528, 10312882883
Offset: 1

Views

Author

Ilya Gutkovskiy, Sep 19 2022

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 39; CoefficientList[Series[Sum[x^(3 k)/(1 - x^k - x^(2 k) - x^(3 k) - x^(4 k)), {k, 1, nmax}], {x, 0, nmax}], x] // Rest

Formula

G.f.: Sum_{k>=1} x^(3*k) / (1 - x^k - x^(2*k) - x^(3*k) - x^(4*k)).
G.f.: Sum_{k>=1} A000078(k) * x^k / (1 - x^k).
a(n) = Sum_{d|n} A000078(d).

A128589 A051731 * A127647.

Original entry on oeis.org

1, 1, 1, 1, 0, 2, 1, 1, 0, 3, 1, 0, 0, 0, 5, 1, 1, 2, 0, 0, 8, 1, 0, 0, 0, 0, 0, 13, 1, 1, 0, 3, 0, 0, 0, 21, 1, 0, 2, 0, 0, 0, 0, 0, 34, 1, 1, 0, 0, 5, 0, 0, 0, 0, 55
Offset: 1

Views

Author

Gary W. Adamson, Mar 11 2007

Keywords

Comments

Row sums = A007435: (1, 2, 3, 5, 6, 12, 14, ...), inverse Moebius transform of the Fibonacci numbers.

Examples

			First few rows of the triangle:
  1;
  1, 1;
  1, 0, 2;
  1, 1, 0, 3;
  1, 0, 0, 0, 5;
  1, 1, 2, 0, 0, 8;
  ...
		

Crossrefs

Formula

Inverse Moebius transform of A127647, as infinite lower triangular matrices.
Previous Showing 11-13 of 13 results.