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.

Showing 1-8 of 8 results.

A151759 G.f.: Theta^3, where Theta = Sum_{k>=0} x^(2^k).

Original entry on oeis.org

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

Views

Author

N. J. A. Sloane, Jun 22 2009

Keywords

Comments

Number of ways to write n as an ordered sum of 3 powers of 2. - Ilya Gutkovskiy, Feb 02 2021

Crossrefs

(Sum_{k>=0} x^(2^k))^m; A209229 (m=1), A073267 (m=2), this sequence (m=3), A151760 (m=4), A151761 (m=5), A151762 (m=6).

Programs

  • Maple
    b:= proc(n, t) option remember; `if`(n=0, `if`(t=0, 1, 0),
          `if`(t<1, 0, add(b(n-2^j, t-1), j=0..ilog2(n))))
        end:
    a:= n-> b(n, 3):
    seq(a(n), n=0..104);  # Alois P. Heinz, Feb 02 2021
  • Mathematica
    b[n_, t_] := b[n, t] = If[n == 0, If[t == 0, 1, 0],
         If[t < 1, 0, Sum[b[n - 2^j, t - 1], {j, 0, Floor@Log2[n]}]]];
    a[n_] := b[n, 3];
    Table[a[n], {n, 0, 104}] (* Jean-François Alcover, Mar 08 2022, after Alois P. Heinz *)

A151761 G.f.: Theta^5, where Theta = Sum_{k>=0} x^(2^k).

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 5, 10, 15, 25, 31, 30, 40, 50, 50, 60, 75, 65, 55, 70, 66, 70, 90, 100, 100, 90, 90, 100, 110, 100, 120, 120, 75, 65, 95, 70, 90, 110, 130, 100, 126, 110, 130, 140, 150, 140, 160, 120, 100, 90, 130, 100, 150, 140, 160, 120, 110, 100, 160, 120, 120, 120, 120
Offset: 0

Views

Author

N. J. A. Sloane, Jun 22 2009

Keywords

Comments

Number of ways to write n as an ordered sum of 5 powers of 2. - Ilya Gutkovskiy, Feb 02 2021

Crossrefs

(Sum_{k>=0} x^(2^k))^m; A209229 (m=1), A073267 (m=2), A151759 (m=3), A151760 (m=4), this sequence (m=5), A151762 (m=6).
Cf. A151758.

Programs

  • Maple
    b:= proc(n, t) option remember; `if`(n=0, `if`(t=0, 1, 0),
          `if`(t<1, 0, add(b(n-2^j, t-1), j=0..ilog2(n))))
        end:
    a:= n-> b(n, 5):
    seq(a(n), n=0..62);  # Alois P. Heinz, Feb 02 2021
  • Mathematica
    b[n_, t_] := b[n, t] = If[n == 0, If[t == 0, 1, 0],
         If[t < 1, 0, Sum[b[n - 2^j, t - 1], {j, 0, Floor@Log2[n]}]]];
    a[n_] := b[n, 5];
    Table[a[n], {n, 0, 62}] (* Jean-François Alcover, Apr 25 2022, after Alois P. Heinz *)

A151758 G.f.: Theta^2-Theta, where Theta = Sum_{k>=0} x^(2^k).

Original entry on oeis.org

0, -1, 0, 2, 0, 2, 2, 0, 0, 2, 2, 0, 2, 0, 0, 0, 0, 2, 2, 0, 2, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 0, 2, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 0, 2, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0
Offset: 0

Views

Author

N. J. A. Sloane, Jun 22 2009

Keywords

Comments

If we omit the "-x" term and divide by 2, we get the characteristic function of the numbers with binary weight 2 (A018900, A151774).

Crossrefs

Programs

  • Mathematica
    w[n_] := IntegerDigits[n, 2] // Total;
    a[n_] := If[n == 1, -1, 2 Boole[w[n] == 2]];
    a /@ Range[0, 104] (* Jean-François Alcover, Mar 31 2021 *)

A342250 Number of ways to write n as an ordered sum of seven powers of 2.

Original entry on oeis.org

1, 7, 21, 42, 77, 126, 168, 218, 294, 357, 427, 546, 637, 672, 756, 840, 854, 966, 1134, 1218, 1302, 1408, 1484, 1554, 1680, 1827, 1995, 2002, 1925, 2016, 1988, 1904, 2142, 2352, 2282, 2352, 2534, 2520, 2604, 2954, 3080, 3276, 3262, 3234, 3150, 3248, 3164, 3402, 3640
Offset: 7

Views

Author

Ilya Gutkovskiy, Mar 07 2021

Keywords

Crossrefs

Programs

  • Maple
    N:= 100:
    S:= add(x^(2^j),j=0..ilog2(N-6))^7:
    [seq](coeff(S,x,j),j=7..N); # Robert Israel, Feb 26 2023
  • Mathematica
    nmax = 55; CoefficientList[Series[Sum[x^(2^k), {k, 0, Floor[Log[2, nmax]] + 1}]^7, {x, 0, nmax}], x] // Drop[#, 7] &

Formula

G.f.: ( Sum_{k>=0} x^(2^k) )^7.

A342251 Number of ways to write n as an ordered sum of eight powers of 2.

Original entry on oeis.org

1, 8, 28, 64, 126, 224, 336, 464, 645, 840, 1044, 1344, 1666, 1904, 2192, 2528, 2730, 3024, 3528, 3920, 4284, 4768, 5168, 5488, 5965, 6552, 7140, 7616, 7834, 8176, 8400, 8352, 8862, 9632, 9800, 10080, 10788, 10976, 11152, 12208, 13090, 13664, 14392, 14672, 14868, 15008, 15344
Offset: 8

Views

Author

Ilya Gutkovskiy, Mar 07 2021

Keywords

Crossrefs

Programs

  • Maple
    N:= 100:
    S:= add(x^(2^j),j=0..ilog2(N-7))^8:
    seq(coeff(S,x,j),j=8..N); # Robert Israel, Feb 26 2023
  • Mathematica
    nmax = 54; CoefficientList[Series[Sum[x^(2^k), {k, 0, Floor[Log[2, nmax]] + 1}]^8, {x, 0, nmax}], x] // Drop[#, 8] &

Formula

G.f.: ( Sum_{k>=0} x^(2^k) )^8.

A342252 Number of ways to write n as an ordered sum of nine powers of 2.

Original entry on oeis.org

1, 9, 36, 93, 198, 378, 624, 927, 1341, 1849, 2412, 3159, 4074, 4950, 5904, 7032, 8010, 9018, 10488, 11970, 13356, 15108, 16848, 18315, 20085, 22257, 24444, 26671, 28674, 30510, 32208, 33282, 34974, 37590, 39384, 40986, 43668, 45468, 46512, 49620, 53298, 55890, 59304, 62442
Offset: 9

Views

Author

Ilya Gutkovskiy, Mar 07 2021

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 52; CoefficientList[Series[Sum[x^(2^k), {k, 0, Floor[Log[2, nmax]] + 1}]^9, {x, 0, nmax}], x] // Drop[#, 9] &

Formula

G.f.: ( Sum_{k>=0} x^(2^k) )^9.

A342254 Number of ways to write n as an ordered sum of ten powers of 2.

Original entry on oeis.org

1, 10, 45, 130, 300, 612, 1095, 1750, 2655, 3850, 5281, 7110, 9460, 12060, 14940, 18352, 21850, 25380, 29790, 34740, 39672, 45480, 51885, 57870, 64375, 72090, 80145, 88630, 97660, 106380, 114736, 122260, 130050, 139740, 148990, 157572, 168240, 178200, 185490, 196200, 210082
Offset: 10

Views

Author

Ilya Gutkovskiy, Mar 07 2021

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 50; CoefficientList[Series[Sum[x^(2^k), {k, 0, Floor[Log[2, nmax]] + 1}]^10, {x, 0, nmax}], x] // Drop[#, 10] &

Formula

G.f.: ( Sum_{k>=0} x^(2^k) )^10.

A347787 Number of compositions (ordered partitions) of n into at most 6 powers of 2.

Original entry on oeis.org

1, 1, 2, 3, 6, 10, 18, 30, 48, 68, 94, 118, 140, 168, 202, 224, 258, 292, 302, 302, 336, 352, 370, 424, 470, 472, 490, 504, 532, 544, 584, 600, 618, 532, 526, 542, 544, 536, 674, 664, 666, 656, 754, 704, 820, 824, 904, 840, 830, 712, 794, 744, 820, 824, 984
Offset: 0

Views

Author

Ilya Gutkovskiy, Sep 13 2021

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Length@Flatten[Permutations/@IntegerPartitions[n,6,Select[Range@n,IntegerQ@Log2@#&]],1],{n,0,54}] (* Giorgos Kalogeropoulos, Sep 13 2021 *)
Showing 1-8 of 8 results.