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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A151687 G.f.: x + x^2 * Product_{n>=0} (1 + x^(2^n-1) + x^(2^n)).

Original entry on oeis.org

0, 1, 2, 3, 3, 3, 5, 6, 4, 3, 5, 6, 6, 8, 11, 10, 5, 3, 5, 6, 6, 8, 11, 10, 7, 8, 11, 12, 14, 19, 21, 15, 6, 3, 5, 6, 6, 8, 11, 10, 7, 8, 11, 12, 14, 19, 21, 15, 8, 8, 11, 12, 14, 19, 21, 17, 15, 19, 23, 26, 33, 40, 36, 21, 7, 3, 5, 6, 6, 8, 11, 10, 7, 8, 11, 12, 14, 19, 21, 15, 8, 8
Offset: 0

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Author

N. J. A. Sloane, Jun 03 2009

Keywords

Comments

Apart from initial terms and offset, same as A160573, but has a slightly nice recurrence.

Crossrefs

Rows of triangle in A118977 converge to this.

Programs

  • Maple
    G:= x + x^2 * mul( 1 + x^(2^n-1) + x^(2^n), n=0..20);

Formula

a(0) = 0, a(2^k) = k+1; for n >= 3, if n = 2^i + j, 1 <= j < 2^i, a(n) = a(j) + a(j+1).

A151683 Irregular triangle read by rows: row n (n>=0) gives binomial(wt(n+k),k), k >= 0, up to the point where the terms are all zeros (wt() = A000120()).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 2, 3, 1, 3, 1, 1, 1, 1, 2, 1, 1, 1, 2, 3, 1, 3, 1, 1, 1, 2, 3, 1, 1, 1, 3, 3, 4, 1, 3, 6, 1, 4, 1, 1, 1, 1, 2, 1, 1, 1, 2, 3, 1, 3, 1, 1, 1, 2, 3, 1, 1, 1, 3, 3, 4, 1, 3, 6, 1, 4, 1, 1, 1, 2, 3, 1, 1, 1, 3, 3, 4, 1, 3, 6, 1, 1, 1, 4, 3, 4, 1, 1, 1, 3
Offset: 0

Views

Author

N. J. A. Sloane, Jun 01 2009

Keywords

Comments

Suggested by Hagen von Eitzen's formula for A160573.

Examples

			The rows for n = 0 .. 36 are:
. 1, 1,
. 1, 1, 1,
. 1, 2,
. 1, 1, 1,
. 1, 2, 1, 1,
. 1, 2, 3,
. 1, 3,
. 1, 1, 1,
. 1, 2, 1, 1,
. 1, 2, 3,
. 1, 3, 1, 1,
. 1, 2, 3, 1, 1,
. 1, 3, 3, 4,
. 1, 3, 6,
. 1, 4,
. 1, 1, 1,
. 1, 2, 1, 1,
. 1, 2, 3,
. 1, 3, 1, 1,
. 1, 2, 3, 1, 1,
. 1, 3, 3, 4,
. 1, 3, 6,
. 1, 4, 1, 1,
. 1, 2, 3, 1, 1,
. 1, 3, 3, 4,
. 1, 3, 6, 1, 1,
. 1, 4, 3, 4, 1, 1,
. 1, 3, 6, 4, 5,
. 1, 4, 6, 10,
. 1, 4, 10,
. 1, 5,
. 1, 1, 1,
. 1, 2, 1, 1,
. 1, 2, 3,
. 1, 3, 1, 1,
. 1, 2, 3, 1, 1,
. 1, 3, 3, 4,
...
		

Crossrefs

Row sums are A160573.

A151684 Let c(n) = x^(2^n-1)*(1-x^(2^n)), g(n) = 1 + x^(2^n-1) + x^(2^n), h(n) = Product_{i=1..n} g(i); then use g.f. (1+2*x) - Sum_{n>=1} c(n)/h(n).

Original entry on oeis.org

1, 1, 1, 0, -1, 1, 1, -1, 0, 0, -2, 1, 2, 0, 2, -1, -5, -1, 1, 3, 7, 1, -8, -8, -6, 3, 18, 16, 0, -17, -31, -21, 19, 51, 47, 3, -70, -106, -48, 71, 170, 156, -18, -243, -318, -132, 253, 564, 455, -130, -819, -1024, -341, 952, 1849, 1355, -606, -2789, -3199, -727, 3410, 5979, 3932, -2678, -9408, -9926, -1281, 12047
Offset: 0

Views

Author

N. J. A. Sloane, Jun 01 2009

Keywords

Comments

This g.f. multiplied by h(k) for k large (cf. A151552) gives the g.f. for (A160573 prefixed by an initial 1).

Crossrefs

A151677 a(n) = sum_{k >= 0} binomial(3*wt(n+k),k), where wt() = A000120().

Original entry on oeis.org

2, 3, 4, 6, 11, 3, 6, 10, 11, 19, 6, 6, 11, 8, 14, 15, 11, 19, 15, 26, 36, 3, 6, 10, 11, 19, 8, 12, 21, 19, 33, 21, 11, 19, 15, 26, 36, 19, 33, 32, 49, 76, 8, 6, 11, 8, 14, 15, 11, 19, 15, 26, 36, 8, 14, 17, 23, 40, 16, 26, 38, 42, 73, 28, 11, 19, 15, 26, 36, 19, 33, 32, 49, 76, 17, 26, 38
Offset: 0

Views

Author

N. J. A. Sloane, Jun 01 2009

Keywords

Comments

Suggested by Hagen von Eitzen's formula for A160573.
Previous Showing 11-14 of 14 results.