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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A342249 Number of partitions of n into nine powers of 2.

Original entry on oeis.org

1, 1, 1, 2, 2, 2, 3, 4, 4, 5, 5, 5, 5, 6, 6, 8, 7, 8, 8, 9, 8, 11, 10, 11, 10, 12, 9, 12, 10, 12, 10, 14, 11, 14, 12, 15, 13, 17, 14, 18, 14, 17, 13, 18, 14, 19, 15, 19, 15, 20, 15, 21, 17, 21, 14, 21, 15, 19, 13, 20, 14, 19, 14, 22, 16, 21, 16, 24, 18, 24, 18, 25
Offset: 9

Views

Author

Ilya Gutkovskiy, Mar 07 2021

Keywords

Crossrefs

A343820 Number of partitions of 2n into powers of 2: p1 <= p2 <= ... <= p_k such that p_i <= 1 + Sum_{j=1..i-1} p_j.

Original entry on oeis.org

1, 1, 2, 3, 6, 8, 12, 15, 26, 32, 42, 50, 68, 80, 98, 113, 166, 192, 230, 262, 318, 360, 418, 468, 572, 640, 732, 812, 934, 1032, 1160, 1273, 1626, 1792, 2010, 2202, 2482, 2712, 3006, 3268, 3682, 4000, 4402, 4762, 5254, 5672, 6190, 6658, 7492, 8064, 8772, 9412
Offset: 0

Views

Author

Alois P. Heinz, Apr 30 2021

Keywords

Examples

			a(2) = 2: [1,1,1,1], [1,1,2].
a(3) = 3: [1,1,1,1,1,1], [1,1,1,1,2], [1,1,2,2].
a(4) = 6: [1,1,1,1,1,1,1,1], [1,1,1,1,1,1,2], [1,1,1,1,2,2], [1,1,2,2,2], [1,1,1,1,4], [1,1,2,4].
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<0, 0, (p->
          `if`(p>n or p>n-p+1, 0, b(n-p, i)))(2^i)+b(n, i-1)))
        end:
    a:= n-> b(2*n, ilog2(n)+1):
    seq(a(n), n=0..80);
  • Mathematica
    b[n_, i_] := b[n, i] = If[n == 0, 1, If[i < 0, 0, Function[p, If[p > n || p > n - p + 1, 0, b[n - p, i]]][2^i] + b[n, i - 1]]];
    a[n_] := b[2n, BitLength[n] + 1];
    Table[a[n], {n, 0, 80}] (* Jean-François Alcover, Feb 13 2023, after Alois P. Heinz *)

Formula

a(n) is odd <=> n in { A000225 }.
a(2^(n-1)) = A002449(n).

A347660 Number of partitions of n into at most 5 powers of 2.

Original entry on oeis.org

1, 1, 2, 2, 4, 4, 5, 4, 7, 5, 7, 5, 8, 5, 7, 4, 8, 5, 8, 5, 10, 6, 8, 4, 9, 5, 8, 4, 8, 4, 5, 1, 8, 5, 8, 5, 11, 6, 8, 4, 11, 6, 9, 4, 9, 4, 5, 1, 9, 5, 8, 4, 9, 4, 5, 1, 8, 4, 5, 1, 5, 1, 1, 0, 8, 5, 8, 5, 11, 6, 8, 4, 12, 6, 9, 4, 9, 4, 5, 1, 11, 6, 9, 4, 10
Offset: 0

Views

Author

Ilya Gutkovskiy, Sep 09 2021

Keywords

Crossrefs

Formula

a(n) = Sum_{k=0..5} A089052(n,k). - Alois P. Heinz, Sep 09 2021

A347661 Number of partitions of n into at most 6 powers of 2.

Original entry on oeis.org

1, 1, 2, 2, 4, 4, 6, 5, 8, 7, 9, 7, 11, 8, 10, 7, 12, 8, 12, 8, 14, 10, 13, 8, 15, 9, 13, 8, 14, 8, 11, 5, 13, 8, 13, 8, 17, 11, 14, 8, 18, 11, 16, 9, 17, 9, 12, 5, 16, 9, 14, 8, 17, 9, 12, 5, 15, 8, 12, 5, 12, 5, 6, 1, 13, 8, 13, 8, 18, 11, 14, 8, 21, 12, 17
Offset: 0

Views

Author

Ilya Gutkovskiy, Sep 09 2021

Keywords

Crossrefs

Formula

a(n) = Sum_{k=0..6} A089052(n,k). - Alois P. Heinz, Sep 09 2021

A088931 G.f.: Sum_{n >= 1} ( x^(2^n)/ ((1+x^(2^(n-1)))*Product_{j=0..n-1} (1-x^(2^j)) ) ).

Original entry on oeis.org

0, 0, 1, 0, 2, 1, 2, 1, 4, 3, 5, 4, 7, 6, 8, 7, 12, 11, 15, 14, 20, 19, 24, 23, 31, 30, 37, 36, 45, 44, 52, 51, 64, 63, 75, 74, 90, 89, 104, 103, 124, 123, 143, 142, 167, 166, 190, 189, 221, 220, 251, 250, 288, 287, 324, 323, 369, 368, 413, 412, 465, 464, 516, 515, 580
Offset: 0

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Author

N. J. A. Sloane, Dec 02 2003

Keywords

Comments

This is the g.f. for the number of non-squashing partitions with a repeated part, that is, A000123(n) - A088567(n).

Examples

			x^2/((1 + x)*(1 - x)) + x^4/((1 + x^2)*(1 - x)*(1 - x^2)) + x^8/((1 + x^4)*(1 - x)*(1 - x^2)*(1 - x^4)) + ...
		

Crossrefs

Apart from initial terms, same as A088980.

Programs

  • Mathematica
    max = 65; Sum[x^(2^n)/((1+x^(2^(n-1))) Product[1-x^(2^j), {j, 0, n-1}]), {n, 1, Log[2, max] // Ceiling}] + O[x]^(max) // CoefficientList[#, x]& (* Jean-François Alcover, Oct 05 2018 *)

A089055 Solution to the non-squashing boxes problem (version 2).

Original entry on oeis.org

2, 4, 8, 16, 28, 46, 72, 108, 156, 218, 298, 398, 524, 678, 868, 1096, 1372, 1698, 2086, 2538, 3070, 3684, 4398, 5214, 6156, 7226, 8450, 9830, 11400, 13162, 15152, 17372, 19868, 22642, 25742, 29170, 32986, 37192, 41850, 46962, 52606, 58784, 65576, 72984, 81106
Offset: 0

Views

Author

N. J. A. Sloane, Dec 04 2003

Keywords

Comments

Given n+1 boxes labeled 0..n, such that box i weighs i grams and can support a total weight of i grams; a(n) = number of stacks of boxes that can be formed such that no box is squashed.

Crossrefs

Cf. A000123, A088567. Equals 2*A089054. Row sums of A089239.

Formula

See A089054 for g.f.

A089300 Number of planar partitions of n (A000219) that are non-squashing along rows and down columns (cf. A018819).

Original entry on oeis.org

1, 1, 3, 4, 9, 13, 25, 33, 56, 76, 122, 170, 264, 360, 538, 707, 1002, 1332, 1853, 2409, 3294
Offset: 0

Views

Author

N. J. A. Sloane, Dec 25 2003

Keywords

Examples

			E.g. a(4) = 9:
4.31.3.22.2.211.21..2..11
.....1....2.....1...1..11
....................1....
		

Crossrefs

Extensions

More terms from Wouter Meeussen, Dec 30 2003

A089688 Table T(n,k), n>=0 and k>=1, read by antidiagonals; the k-th row is defined by : partitions of k*n into powers of k (with T(0,k) = 1).

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 4, 2, 1, 1, 6, 3, 2, 1, 1, 10, 5, 3, 2, 1, 1, 14, 7, 4, 3, 2, 1, 1, 20, 9, 6, 4, 3, 2, 1, 1, 26, 12, 8, 5, 4, 3, 2, 1, 1, 36, 15, 10, 7, 5, 4, 3, 2, 1, 1, 46, 18, 12, 9, 6, 5, 4, 3, 2, 1, 1, 60, 23, 15, 11, 8, 6, 5, 4, 3, 2, 1
Offset: 0

Views

Author

Philippe Deléham, Jan 05 2004

Keywords

Examples

			Row k = 1 : 1, 1, 1, 1,  1,  1,  1,  1,  1,  1,  1,  1, ... (see A000012).
Row k = 2 : 1, 2, 4, 6, 10, 14, 20, 26, 36, 46, 60, 74, ... (see A000123).
Row k = 3 : 1, 2, 3, 5,  7,  9, 12, 15, 18, 23, 28, 33, ... (see A005704).
Row k = 4 : 1, 2, 3, 4,  6,  8, 10, 12, 15, 18, 21, 24, ... (see A005705).
Row k = 5 : 1, 2, 3, 4,  5,  7,  9, 11, 13, 15, 18, 21, ... (see A005706).
		

A102379 a(n) is the minimal number of nodes in a binary tree of height n.

Original entry on oeis.org

0, 1, 2, 4, 6, 9, 12, 17, 22, 29, 36, 46, 56, 69, 82, 100, 118, 141, 164, 194, 224, 261, 298, 345, 392, 449, 506, 576, 646, 729, 812, 913, 1014, 1133, 1252, 1394, 1536, 1701, 1866, 2061, 2256, 2481, 2706, 2968, 3230, 3529, 3828, 4174, 4520, 4913
Offset: 1

Views

Author

Mitch Harris, Jan 05 2005

Keywords

Comments

Conjecture: Let b(n) be the number of fixed points of the set of binary partitions of n under Glaisher's function that proves Euler's odd-distinct theorem. Then b(1) = 1 and for n > 1, b(2*n) = b(2*n+1) = 2*a(n). - George Beck, Jul 23 2022

References

  • de Bruijn, N. G., On Mahler's partition problem. Nederl. Akad. Wetensch., Proc. 51, (1948) 659-669 = Indagationes Math. 10, 210-220 (1948).
  • Gonnet, Gaston H.; Olivie, Henk J.; and Wood, Derick, Height-ratio-balanced trees. Comput. J. 26 (1983), no. 2, 106-108.
  • Mahler, Kurt On a special functional equation. J. London Math. Soc. 15, (1940). 115-123.
  • Nievergelt, J.; Reingold, E. M., Binary search trees of bounded balance, SIAM J. Comput. 2 (1973), 33-43.

Crossrefs

Essentially partial sums of A040039.

Programs

  • Python
    from functools import cache
    @cache
    def a(n: int) -> int:
        return a(n - 1) + a(n // 2) + 1 if n > 1 else 0
    print([a(n) for n in range(1, 51)])  # Peter Luschny, Jul 24 2022

Formula

a(n) = a(n-1) + a(floor(n/2)) + 1, a(1) = 0.
a(n) - a(n-1) = A018819(n+1).
G.f. A(x) satisfies (1-x)*A(x) = 2*(1 + x)*B(x^2), where B(x) is the g.f. of A033485.

A145523 Least integer k > 0 such that A000041(k) is divisible by 2^n.

Original entry on oeis.org

1, 2, 11, 11, 15, 66, 66, 96, 96, 96, 96, 96, 3693, 15005, 18978, 18978, 18978, 43002, 55943, 972190, 1151214, 2799146, 15519397, 15519397, 15519397, 122101417, 210553237, 289585489, 473093534
Offset: 0

Views

Author

M. F. Hasler, Oct 12 2008

Keywords

Comments

The requirement a(n) > 0 is somewhat arbitrary, chosen for agreement with A046641; a(n) >= 0 would have been possible, too, yielding a(0)=0.
a(29) > 10^9.

Crossrefs

Programs

  • sh
    i=1; c=1; while [ $c -le 21 ]; do echo -n `./A046641 $i`", "; c=`expr $c + 1`; i=`expr $i + $i`; done # M. F. Hasler, Oct 18 2008

Formula

a(n) = A046641(2^n).

Extensions

More terms from M. F. Hasler, Oct 18 2008
a(22)-a(28) from Max Alekseyev, Dec 16 2011
Previous Showing 71-80 of 109 results. Next