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 11-20 of 34 results. Next

A328546 Number of 12-regular partitions of n (no part is a multiple of 12).

Original entry on oeis.org

1, 1, 2, 3, 5, 7, 11, 15, 22, 30, 42, 56, 76, 100, 133, 173, 226, 290, 374, 475, 605, 762, 960, 1199, 1497, 1856, 2299, 2831, 3482, 4261, 5208, 6337, 7700, 9321, 11266, 13572, 16325, 19578, 23444, 27999, 33389, 39721, 47185, 55929, 66199, 78199, 92246
Offset: 0

Views

Author

N. J. A. Sloane, Oct 19 2019

Keywords

References

  • Kathiravan, T., and S. N. Fathima. "On L-regular bipartitions modulo L." The Ramanujan Journal 44.3 (2017): 549-558.

Crossrefs

Number of r-regular partitions for r = 2 through 12: A000009, A000726, A001935, A035959, A219601, A035985, A261775, A104502, A261776, A328545, A328546.

Programs

  • Maple
    f:=(k,M) -> mul(1-q^(k*j),j=1..M);
    LRP := (L,M) -> f(L,M)/f(1,M);
    s := L -> seriestolist(series(LRP(L,80),q,60));
    s(12);
  • Mathematica
    Table[Count[IntegerPartitions@n, x_ /; ! MemberQ [Mod[x, 12], 0, 2] ], {n, 0, 46}] (* Robert Price, Jul 28 2020 *)

Formula

a(n) ~ exp(Pi*sqrt(2*n*(s-1)/(3*s))) * (s-1)^(1/4) / (2 * 6^(1/4) * s^(3/4) * n^(3/4)) * (1 + ((s-1)^(3/2)*Pi/(24*sqrt(6*s)) - 3*sqrt(6*s) / (16*Pi * sqrt(s-1))) / sqrt(n) + ((s-1)^3*Pi^2/(6912*s) - 45*s/(256*(s-1)*Pi^2) - 5*(s-1)/128) / n), set s=12. - Vaclav Kotesovec, Aug 01 2022

A286653 Square array A(n,k), n>=0, k>=1, read by antidiagonals, where column k is the expansion of Product_{j>=1} (1 - x^(k*j))/(1 - x^j).

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 2, 2, 0, 1, 1, 2, 2, 2, 0, 1, 1, 2, 3, 4, 3, 0, 1, 1, 2, 3, 4, 5, 4, 0, 1, 1, 2, 3, 5, 6, 7, 5, 0, 1, 1, 2, 3, 5, 6, 9, 9, 6, 0, 1, 1, 2, 3, 5, 7, 10, 12, 13, 8, 0, 1, 1, 2, 3, 5, 7, 10, 13, 16, 16, 10, 0, 1, 1, 2, 3, 5, 7, 11, 14, 19, 22, 22, 12, 0
Offset: 0

Views

Author

Ilya Gutkovskiy, May 11 2017

Keywords

Comments

A(n,k) is the number of partitions of n in which no parts are multiples of k.
A(n,k) is also the number of partitions of n into at most k-1 copies of each part.

Examples

			Square array begins:
  1,  1,  1,  1,  1,  1,  ...
  0,  1,  1,  1,  1,  1,  ...
  0,  1,  2,  2,  2,  2,  ...
  0,  2,  2,  3,  3,  3,  ...
  0,  2,  4,  4,  5,  5,  ...
  0,  3,  5,  6,  6,  7,  ...
		

Crossrefs

Main diagonal gives A000041.
Mirror of A061198.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0, [1, 0], `if`(k*i*(i+1)/2[0, l[1]*j]+l)(b(n-i*j, i-1, k)), j=0..min(n/i, k))))
        end:
    A:= (n, k)-> b(n$2, k-1)[1]:
    seq(seq(A(n, 1+d-n), n=0..d), d=0..16);  # Alois P. Heinz, Oct 17 2018
  • Mathematica
    Table[Function[k, SeriesCoefficient[Product[(1 - x^(i k))/(1 - x^i), {i, Infinity}], {x, 0, n}]][j - n + 1], {j, 0, 12}, {n, 0, j}] // Flatten
    Table[Function[k, SeriesCoefficient[QPochhammer[x^k, x^k]/QPochhammer[x, x], {x, 0, n}]][j - n + 1], {j, 0, 12}, {n, 0, j}] // Flatten

Formula

G.f. of column k: Product_{j>=1} (1 - x^(k*j))/(1 - x^j).

A121591 Expansion of (eta(q^5) / eta(q))^6 in powers of q.

Original entry on oeis.org

1, 6, 27, 98, 315, 912, 2456, 6210, 14937, 34390, 76317, 163896, 342062, 695736, 1382880, 2691586, 5139906, 9644622, 17808040, 32393370, 58113312, 102914152, 180062622, 311488920, 533124225, 903324372, 1516110165, 2521780688, 4158863310, 6803237280, 11043320922, 17794350786
Offset: 1

Views

Author

Michael Somos, Aug 09 2006

Keywords

Examples

			G.f. = q + 6*q^2 + 27*q^3 + 98*q^4 + 315*q^5 + 912*q^6 + 2456*q^7 + 6210*q^8 + ...
		

Crossrefs

Programs

  • Mathematica
    a[ n_] := SeriesCoefficient[ q (QPochhammer[ q^5] / QPochhammer[ q])^6, {q, 0, n}]; (* Michael Somos, May 22 2013 *)
    nmax = 40; Rest[CoefficientList[Series[x * Product[((1 - x^(5*k)) / (1 - x^k))^6, {k, 1, nmax}], {x, 0, nmax}], x]] (* Vaclav Kotesovec, Sep 07 2015 *)
  • PARI
    {a(n) = my(A); if( n<1, 0, n--; A = x * O(x^n); polcoeff( (eta(x^5 + A) / eta(x + A))^6, n))};

Formula

Euler transform of period 5 sequence [6, 6, 6, 6, 0, ...].
G.f. A(x) satisfies 0 = f(A(x), A(x^2)) where f(u, v) = u*v * (1 + 125 * u*v) - (u+v) * (u^2 - 13 * u*v + v^2). - Michael Somos, May 22 2013
G.f. is a period 1 Fourier series which satisfies f(-1 / (5 t)) = 1/125 g(t) where q = exp(2 Pi i t) and g() is the g.f. for A106248. - Michael Somos, May 22 2013
G.f.: x * (Product_{k>0} (1 - x^(5*k)) / (1 - x^k))^6.
Convolution inverse of A106248, 6th power of A035959. - Michael Somos, Aug 09 2015
a(n) ~ exp(4*Pi*sqrt(n/5)) / (125 * sqrt(2) * 5^(1/4) * n^(3/4)). - Vaclav Kotesovec, Sep 07 2015
a(1) = 1, a(n) = (6/(n-1))*Sum_{k=1..n-1} A116073(k)*a(n-k) for n > 1. - Seiichi Manyama, Mar 31 2017

A145466 Expansion of q^(1/6) * eta(q) / eta(q^5) in powers of q.

Original entry on oeis.org

1, -1, -1, 0, 0, 2, -1, 0, 0, 0, 3, -2, -2, 0, 0, 4, -3, -2, 0, 0, 7, -5, -3, 0, 0, 10, -6, -4, 0, 0, 15, -10, -7, 0, 0, 20, -13, -8, 0, 0, 28, -19, -13, 0, 0, 38, -25, -16, 0, 0, 52, -34, -23, 0, 0, 68, -44, -28, 0, 0, 91, -60, -40, 0, 0, 118, -76, -48, 0, 0, 153, -100, -66, 0, 0, 196, -127, -82, 0, 0, 252, -164, -107, 0, 0
Offset: 0

Views

Author

Michael Somos, Oct 11 2008

Keywords

Examples

			G.f. = 1 - x - x^2 + 2*x^5 - x^6 + 3*x^10 - 2*x^11 - 2*x^12 + 4*x^15 + ...
G.f. = 1/q - q^5 - q^11 + 2*q^29 - q^35 + 3*q^59 - 2*q^65 - 2*q^71 + 4*q^89 + ...
		

Crossrefs

Programs

  • Mathematica
    a[ n_] := SeriesCoefficient[ QPochhammer[ x] / QPochhammer[ x^5], {x, 0, n}]; (* Michael Somos, Jun 26 2014 *)
  • PARI
    {a(n) = local(A); if( n<0, 0, A = x * O(x^n); polcoeff( eta(x + A) / eta(x^5 + A), n))};

Formula

Expansion of 1 / (G(x) * H(x)) = G(x^5)^2 - x * G(x^5) * H(x^5) - x^2 * H(x^5)^2 in powers of x where G(), H() are the Rogers-Ramanujan functions.
Euler transform of period 5 sequence [ -1, -1, -1, -1, 0, ...].
G.f. is a period 1 Fourier series which satisfies f(-1 / (180 t)) = 5^(1/2) g(t) where q = exp(2 Pi i t) and g() is the g.f. of A035959.
Given g.f. A(x), then B(x) = A(x^3)^2 / x satisfies 0 = f(B(x), B(x^2)) where f(u, v) = u^3 + v^3 - 5*u*v - u^2*v^2.
Given g.f. A(x), then B(x) = A(x^3)^2 / x satisfies 0 = f(B(x), B(x^2), B(x^4)) where f(u, v, w) = v * u^2 * w^2 + 5 * u * w * (u + w) - v^2 * (u^2 + u*w + w^2).
a(5*n + 3) = a(5*n + 4) = 0.
G.f.: 1 / (Product_{k>0} P(5, x^k)) where P(n,x) is the n-th cyclotomic polynomial.
a(5*n) = A145467(n). a(5*n + 1) = - A035969(n). a(5*n + 2) = - A145468(n).
Convolution inverse of A035959.
a(n) = -(1/n)*Sum_{k=1..n} A116073(k)*a(n-k), a(0) = 1. - Seiichi Manyama, Mar 25 2017

A061199 Upper right triangle read by columns where T(n,k), with k >= n, is the number of partitions of k where no part appears more than n times; also partitions of k where no parts are multiples of (n+1).

Original entry on oeis.org

1, 0, 1, 0, 1, 2, 0, 2, 2, 3, 0, 2, 4, 4, 5, 0, 3, 5, 6, 6, 7, 0, 4, 7, 9, 10, 10, 11, 0, 5, 9, 12, 13, 14, 14, 15, 0, 6, 13, 16, 19, 20, 21, 21, 22, 0, 8, 16, 22, 25, 27, 28, 29, 29, 30, 0, 10, 22, 29, 34, 37, 39, 40, 41, 41, 42, 0, 12, 27, 38, 44, 49, 51, 53, 54, 55, 55, 56, 0, 15, 36
Offset: 0

Views

Author

Henry Bottomley, Apr 20 2001

Keywords

Examples

			T(2,4) = 4 since the possible partitions of 4 are on the first definition (no term more than twice) 1+1+2, 2+2, 1+3, or 4 and on the second definition (no term a multiple of 3) 1+1+1+1, 1+1+2, 2+2, or 4.
Triangle T(n,k) begins:
1, 0, 0, 0, 0, 0,  0,  0,  0,  0, ...
   1, 1, 2, 2, 3,  4,  5,  6,  8, ...
      2, 2, 4, 5,  7,  9, 13, 16, ...
         3, 4, 6,  9, 12, 16, 22, ...
            5, 6, 10, 13, 19, 25, ...
               7, 10, 14, 20, 27, ...
                  11, 14, 21, 28, ...
                      15, 21, 29, ...
                          22, 29, ...
                              30, ...
		

Crossrefs

Rows effectively include A000007, A000009, A000726, A001935, A035959.
Main diagonal is A000041.
A061198 is the same table but includes cases where n>k.
T(n,2*n) gives: A232623.

Programs

  • Maple
    b:= proc(n, i, k) option remember;
          `if`(n=0, 1, `if`(i<1, 0,
          add(b(n-i*j, i-1, k), j=0..min(n/i, k))))
        end:
    T:= (n, k)-> b(k$2, n):
    seq(seq(T(n, k), n=0..k), k=0..12);  # Alois P. Heinz, Nov 27 2013
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n == 0, 1, If[i<1, 0, Sum[b[n - i*j, i-1, k], {j, 0, Min[n/i, k]}]]]; T[n_, k_] := b[k, k, n]; Table[Table[T[n, k], {n, 0, k}], {k, 0, 12}] // Flatten (* Jean-François Alcover, Jan 28 2015, after Alois P. Heinz *)

A107234 Expansion of 1 / Product_{n>=0} (1-q^(5n+1))(1-q^(5n+2))(1-q^(5n+3)).

Original entry on oeis.org

1, 1, 2, 3, 4, 5, 8, 10, 14, 18, 23, 29, 38, 47, 60, 74, 92, 112, 139, 168, 205, 247, 298, 356, 429, 509, 607, 718, 850, 1000, 1180, 1381, 1620, 1890, 2206, 2564, 2983, 3453, 4000, 4618, 5330, 6133, 7059, 8097, 9289, 10630, 12159, 13877
Offset: 0

Views

Author

Ralf Stephan, May 13 2005

Keywords

Comments

a(n) is the number of partitions of n into parts 5k+1, 5k+2 or 5k+3. - George Beck, Aug 09 2020

Crossrefs

Programs

  • Mathematica
    nmax = 50; CoefficientList[Series[1/Product[(1 - x^(5*k+1))*(1 - x^(5*k+2))*(1 - x^(5*k+3)), {k, 0, nmax/5}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Jan 07 2021 *)

Formula

a(n) ~ Pi^(1/5) * exp(Pi*sqrt(2*n/5)) / (Gamma(4/5) * 2^(3/5) * 5^(9/10) * n^(3/5)). - Vaclav Kotesovec, Jan 07 2021

A107235 Expansion of 1 / Product_{n>=0} (1 - q^(5n+1))*(1 - q^(5n+2))*(1 - q^(5n+4)).

Original entry on oeis.org

1, 1, 2, 2, 4, 4, 7, 8, 12, 14, 19, 23, 31, 37, 48, 57, 73, 86, 109, 128, 159, 187, 229, 269, 326, 382, 458, 535, 638, 742, 879, 1019, 1200, 1388, 1625, 1875, 2185, 2514, 2916, 3347, 3868, 4427, 5099, 5822, 6683, 7614, 8712, 9904, 11301, 12821, 14589
Offset: 0

Views

Author

Ralf Stephan, May 13 2005

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 50; CoefficientList[Series[1/Product[(1 - x^(5*k+1))*(1 - x^(5*k+2))*(1 - x^(5*k+4)), {k, 0, nmax/5}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Jan 07 2021 *)

Formula

a(n) ~ Pi^(2/5) * exp(Pi*sqrt(2*n/5)) / (Gamma(3/5) * 2^(7/10) * 5^(4/5) * n^(7/10)). - Vaclav Kotesovec, Jan 07 2021

A107236 Expansion of 1 / Product_{n>=0} (1 - q^(5n+1))*(1 - q^(5n+3))*(1 - q^(5n+4)).

Original entry on oeis.org

1, 1, 1, 2, 3, 3, 5, 6, 8, 11, 13, 16, 22, 26, 32, 40, 49, 59, 73, 87, 105, 126, 151, 178, 214, 252, 297, 351, 413, 481, 566, 658, 767, 892, 1034, 1195, 1386, 1595, 1838, 2114, 2429, 2781, 3189, 3642, 4160, 4744, 5404, 6141, 6986, 7921, 8980
Offset: 0

Views

Author

Ralf Stephan, May 13 2005

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 50; CoefficientList[Series[1/Product[(1 - x^(5*k+1))*(1 - x^(5*k+3))*(1 - x^(5*k+4)), {k, 0, nmax/5}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Jan 07 2021 *)

Formula

a(n) ~ Pi^(3/5) * exp(Pi*sqrt(2*n/5)) / (Gamma(2/5) * 2^(4/5) * 5^(7/10) * n^(4/5)). - Vaclav Kotesovec, Jan 07 2021

A107237 Expansion of 1 / Product_{n>=0} (1 - q^(5n+2))*(1 - q^(5n+3))*(1 - q^(5n+4)).

Original entry on oeis.org

1, 0, 1, 1, 2, 1, 3, 3, 5, 5, 7, 8, 12, 12, 17, 19, 26, 28, 37, 41, 53, 60, 74, 84, 105, 118, 144, 164, 198, 224, 269, 305, 362, 411, 484, 550, 645, 729, 850, 964, 1117, 1262, 1458, 1647, 1894, 2137, 2446, 2757, 3150, 3542, 4031
Offset: 0

Views

Author

Ralf Stephan, May 13 2005

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 50; CoefficientList[Series[1/Product[(1 - x^(5*k+2))*(1 - x^(5*k+3))*(1 - x^(5*k+4)), {k, 0, nmax/5}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Jan 07 2021 *)

Formula

a(n) ~ Pi^(4/5) * exp(Pi*sqrt(2*n/5)) / (Gamma(1/5) * 2^(9/10) * 5^(3/5) * n^(9/10)). - Vaclav Kotesovec, Jan 07 2021

A285928 Expansion of (Product_{k>0} (1 - x^(5*k)) / (1 - x^k))^5 in powers of x.

Original entry on oeis.org

1, 5, 20, 65, 190, 501, 1240, 2890, 6440, 13775, 28502, 57205, 111880, 213670, 399620, 733128, 1321850, 2345340, 4100700, 7072520, 12045005, 20272465, 33746060, 55595635, 90706390, 146638756, 235016940, 373580735, 589238640, 922537655, 1434232510, 2214817165
Offset: 0

Views

Author

Seiichi Manyama, Apr 28 2017

Keywords

Comments

In general, if m > 1 and g.f. = Product_{k>=1} ((1 - x^(m*k)) / (1 - x^k))^m, then a(n, m) ~ exp(Pi*sqrt(2*(m-1)*n/3)) * (m-1)^(1/4) / (2^(5/4) * 3^(1/4) * m^(m/2) * n^(3/4)). - Vaclav Kotesovec, Apr 30 2017

Crossrefs

(Product_{k>0} (1 - x^(m*k)) / (1 - x^k))^m: A022567 (m=2), A285927 (m=3), A093160 (m=4), this sequence (m=5).

Programs

  • Mathematica
    nmax = 40; CoefficientList[Series[Product[((1 - x^(5*k)) / (1 - x^k))^5, {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Apr 30 2017 *)

Formula

a(0) = 1, a(n) = (5/n)*Sum_{k=1..n} A116073(k)*a(n-k) for n > 0.
a(n) ~ exp(2*Pi*sqrt(2*n/3)) / (2^(3/4) * 3^(1/4) * 5^(5/2) * n^(3/4)). - Vaclav Kotesovec, Apr 30 2017
Previous Showing 11-20 of 34 results. Next