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 1-3 of 3 results.

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

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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).

A355358 Coefficients in the expansion of A(x) = 1 / Product_{n>=0} (1 - x^(13*n+1))*(1 - x^(13*n+3))*(1 - x^(13*n+4))*(1 - x^(13*n+9))*(1 - x^(13*n+10))*(1 - x^(13*n+12)).

Original entry on oeis.org

1, 1, 1, 2, 3, 3, 4, 5, 6, 8, 10, 11, 15, 18, 21, 25, 31, 36, 43, 50, 59, 69, 81, 93, 109, 126, 146, 168, 194, 222, 256, 291, 333, 379, 432, 489, 557, 629, 712, 805, 909, 1021, 1152, 1293, 1452, 1627, 1824, 2037, 2281, 2544, 2838, 3162, 3525, 3916, 4356
Offset: 0

Views

Author

Paul D. Hanna, Jul 31 2022

Keywords

Examples

			G.f.: A(x) = 1 + x + x^2 + 2*x^3 + 3*x^4 + 3*x^5 + 4*x^6 + 5*x^7 + 6*x^8 + 8*x^9 + 10*x^10 + 11*x^11 + 15*x^12 + 18*x^13 + 21*x^14 + ...
and the related series B(x) begins
B(x) = 1 + x^2 + x^4 + x^5 + 2*x^6 + 2*x^7 + 3*x^8 + 2*x^9 + 4*x^10 + 4*x^11 + 6*x^12 + 6*x^13 + 8*x^14 + 9*x^15 + ... + A355359(n)*x^n + ...
such that A(x) and B(x) satisfy
1 = A(x^3)*B(x) - x^2*A(x)*B(x^3),
and
1 = A(x)^3*B(x) - x^2*A(x)*B(x)^3 - 3*x*A(x)^2*B(x)^2.
Related expansions begin
A(x^3)*B(x) = 1 + x^2 + x^3 + x^4 + 2*x^5 + 3*x^6 + 3*x^7 + 5*x^8 + 6*x^9 + 7*x^10 + 10*x^11 + 13*x^12 + 14*x^13 + 20*x^14 + 24*x^15 + ...
A(x)*B(x^3) = 1 + x + x^2 + 2*x^3 + 3*x^4 + 3*x^5 + 5*x^6 + 6*x^7 + 7*x^8 + 10*x^9 + 13*x^10 + ...
A(x)^3*B(x) = 1 + 3*x + 7*x^2 + 16*x^3 + 34*x^4 + 65*x^5 + 120*x^6 + 213*x^7 + 365*x^8 + 609*x^9 + 994*x^10 + ...
A(x)*B(x)^3 = 1 + x + 4*x^2 + 5*x^3 + 12*x^4 + 18*x^5 + 35*x^6 + 54*x^7 + 94*x^8 + 142*x^9 + 232*x^10 + ...
A(x)^2*B(x)^2 = 1 + 2*x + 5*x^2 + 10*x^3 + 20*x^4 + 36*x^5 + 65*x^6 + 110*x^7 + 185*x^8 + 300*x^9 + 481*x^10 + ...
		

Crossrefs

Programs

  • Mathematica
    nmax = 60; CoefficientList[Series[1/Product[(1 - x^(13*n + 1))*(1 - x^(13*n + 3))*(1 - x^(13*n + 4))*(1 - x^(13*n + 9))*(1 - x^(13*n + 10))*(1 - x^(13*n + 12)), {n, 0, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Aug 01 2022 *)
  • PARI
    {a(n) = polcoeff( 1/prod(m=0, n, (1 - x^(13*m+1))*(1 - x^(13*m+3))*(1 - x^(13*m+4))*(1 - x^(13*m+9))*(1 - x^(13*m+10))*(1 - x^(13*m+12)), 1 + x*O(x^n)), n)};
    for(n=0,60,print1(a(n),", "))
    
  • PARI
    {a(n) = polcoeff( sqrt( prod(k=1, n, (1 - x^(13*k))/(1 - x^k)^(1 + kronecker(13, k)), 1 + x*O(x^n)) ), n)};
    for(n=0,60,print1(a(n),", "))

Formula

G.f. A(x) = Sum_{n>=0} a(n)*x^n and related function B(x) satisfy the following relations.
(1.a) A(x^3)*B(x) - x^2*A(x)*B(x^3) = 1.
(1.b) A(x)^3*B(x) - x^2*A(x)*B(x)^3 - 3*x*A(x)^2*B(x)^2 = 1.
(2.a) A(x) = 1 / Product_{n>=0} (1 - x^(13*n+1))*(1 - x^(13*n+3))*(1 - x^(13*n+4))*(1 - x^(13*n+9))*(1 - x^(13*n+10))*(1 - x^(13*n+12)).
(2.b) B(x) = 1 / Product_{n>=0} (1 - x^(13*n+2))*(1 - x^(13*n+5))*(1 - x^(13*n+6))*(1 - x^(13*n+7))*(1 - x^(13*n+8))*(1 - x^(13*n+11)).
(3.a) A(x)*B(x) = Product_{n>=1} (1 - x^(13*n))/(1 - x^n), a g.f. of A341714.
(3.b) A(x)/B(x) = Product_{n>=1} 1/(1 - x^n)^Kronecker(13, n), a g.f. of A214157.
(4.a) A(x) = sqrt( Product_{n>=1} (1 - x^(13*n))/(1 - x^n)^(1 + Kronecker(13, n)) ).
(4.b) B(x) = sqrt( Product_{n>=1} (1 - x^(13*n))/(1 - x^n)^(1 - Kronecker(13, n)) ).
(5.a) A(x) = ( Product_{n>=1} (1 - x^(13*n))^3 ) / ( f(-x, -x^12) * f(-x^3, -x^10) * f(-x^4, -x^9) ).
(5.b) B(x) = ( Product_{n>=1} (1 - x^(13*n))^3 ) / ( f(-x^2, -x^11) * f(-x^5, -x^8) * f(-x^6, -x^7) ) .
Formulas (4.*) and (5.*) are derived from formulas given by Michael Somos in A214157, where f(a,b) = Sum_{n=-oo..+oo} a^(n*(n+1)/2) * b^(n*(n-1)/2) is Ramanujan's theta function..
a(n) ~ exp(2*Pi*sqrt(n/13)) / (16 * 13^(1/4) * sin(Pi/13) * sin(3*Pi/13) * cos(5*Pi/26) * n^(3/4)). - Vaclav Kotesovec, Aug 01 2022

A355359 Coefficients in the expansion of B(x) = 1 / Product_{n>=0} (1 - x^(13*n+2))*(1 - x^(13*n+5))*(1 - x^(13*n+6))*(1 - x^(13*n+7))*(1 - x^(13*n+8))*(1 - x^(13*n+11)).

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 2, 2, 3, 2, 4, 4, 6, 6, 8, 9, 11, 12, 16, 17, 22, 24, 29, 32, 39, 43, 53, 57, 69, 75, 90, 99, 117, 129, 150, 166, 193, 213, 246, 273, 312, 346, 394, 436, 496, 549, 621, 687, 774, 855, 962, 1062, 1192, 1313, 1470, 1618, 1807, 1989, 2214, 2436
Offset: 0

Views

Author

Paul D. Hanna, Aug 01 2022

Keywords

Examples

			G.f.: B(x) = 1 + x^2 + x^4 + x^5 + 2*x^6 + 2*x^7 + 3*x^8 + 2*x^9 + 4*x^10 + 4*x^11 + 6*x^12 + 6*x^13 + 8*x^14 + 9*x^15 + ...
and the related series A(x) begins
A(x) = 1 + x + x^2 + 2*x^3 + 3*x^4 + 3*x^5 + 4*x^6 + 5*x^7 + 6*x^8 + 8*x^9 + 10*x^10 + 11*x^11 + 15*x^12 + 18*x^13 + 21*x^14 + ... + A355358(n)*x^n + ...
such that A(x) and B(x) satisfy
1 = A(x^3)*B(x) - x^2*A(x)*B(x^3),
and
1 = A(x)^3*B(x) - x^2*A(x)*B(x)^3 - 3*x*A(x)^2*B(x)^2.
Related expansions begin
A(x^3)*B(x) = 1 + x^2 + x^3 + x^4 + 2*x^5 + 3*x^6 + 3*x^7 + 5*x^8 + 6*x^9 + 7*x^10 + 10*x^11 + 13*x^12 + 14*x^13 + 20*x^14 + 24*x^15 + ...
A(x)*B(x^3) = 1 + x + x^2 + 2*x^3 + 3*x^4 + 3*x^5 + 5*x^6 + 6*x^7 + 7*x^8 + 10*x^9 + 13*x^10 + ...
A(x)^3*B(x) = 1 + 3*x + 7*x^2 + 16*x^3 + 34*x^4 + 65*x^5 + 120*x^6 + 213*x^7 + 365*x^8 + 609*x^9 + 994*x^10 + ...
A(x)*B(x)^3 = 1 + x + 4*x^2 + 5*x^3 + 12*x^4 + 18*x^5 + 35*x^6 + 54*x^7 + 94*x^8 + 142*x^9 + 232*x^10 + ...
A(x)^2*B(x)^2 = 1 + 2*x + 5*x^2 + 10*x^3 + 20*x^4 + 36*x^5 + 65*x^6 + 110*x^7 + 185*x^8 + 300*x^9 + 481*x^10 + ...
		

Crossrefs

Programs

  • Mathematica
    nmax = 60; CoefficientList[Series[1/Product[(1 - x^(13*n + 2))*(1 - x^(13*n + 5))*(1 - x^(13*n + 6))*(1 - x^(13*n + 7))*(1 - x^(13*n + 8))*(1 - x^(13*n + 11)), {n, 0, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Aug 01 2022 *)
  • PARI
    {a(n) = polcoeff( 1/prod(m=0, n, (1 - x^(13*m+2))*(1 - x^(13*m+5))*(1 - x^(13*m+6))*(1 - x^(13*m+7))*(1 - x^(13*m+8))*(1 - x^(13*m+11)), 1 + x*O(x^n)), n)};
    for(n=0,60,print1(a(n),", "))
    
  • PARI
    {a(n) = polcoeff( sqrt( prod(k=1, n, (1 - x^(13*k))/(1 - x^k)^(1 - kronecker(13, k)), 1 + x*O(x^n)) ), n)};
    for(n=0,60,print1(a(n),", "))

Formula

G.f. B(x) = Sum_{n>=0} a(n)*x^n and related function A(x) satisfy the following relations.
(1.a) A(x^3)*B(x) - x^2*A(x)*B(x^3) = 1.
(1.b) A(x)^3*B(x) - x^2*A(x)*B(x)^3 - 3*x*A(x)^2*B(x)^2 = 1.
(2.a) A(x) = 1 / Product_{n>=0} (1 - x^(13*n+1))*(1 - x^(13*n+3))*(1 - x^(13*n+4))*(1 - x^(13*n+9))*(1 - x^(13*n+10))*(1 - x^(13*n+12)).
(2.b) B(x) = 1 / Product_{n>=0} (1 - x^(13*n+2))*(1 - x^(13*n+5))*(1 - x^(13*n+6))*(1 - x^(13*n+7))*(1 - x^(13*n+8))*(1 - x^(13*n+11)).
(3.a) A(x)*B(x) = Product_{n>=1} (1 - x^(13*n))/(1 - x^n), a g.f. of A341714.
(3.b) A(x)/B(x) = Product_{n>=1} 1/(1 - x^n)^Kronecker(13, n), a g.f. of A214157.
(4.a) A(x) = sqrt( Product_{n>=1} (1 - x^(13*n))/(1 - x^n)^(1 + Kronecker(13, n)) ).
(4.b) B(x) = sqrt( Product_{n>=1} (1 - x^(13*n))/(1 - x^n)^(1 - Kronecker(13, n)) ).
(5.a) A(x) = ( Product_{n>=1} (1 - x^(13*n))^3 ) / ( f(-x, -x^12) * f(-x^3, -x^10) * f(-x^4, -x^9) ).
(5.b) B(x) = ( Product_{n>=1} (1 - x^(13*n))^3 ) / ( f(-x^2, -x^11) * f(-x^5, -x^8) * f(-x^6, -x^7) ) .
Formulas (4.*) and (5.*) are derived from formulas given by Michael Somos in A214157, where f(a,b) = Sum_{n=-oo..+oo} a^(n*(n+1)/2) * b^(n*(n-1)/2) is Ramanujan's theta function..
a(n) ~ exp(2*Pi*sqrt(n/13)) / (16 * 13^(1/4) * sin(2*Pi/13) * cos(Pi/26) * cos(3*Pi/26) * n^(3/4)). - Vaclav Kotesovec, Aug 01 2022
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