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 1-10 of 35 results. Next

A276551 Convolution square of A073592.

Original entry on oeis.org

1, -2, -3, 2, 6, 12, 1, -10, -32, -46, -24, 18, 96, 168, 213, 124, -61, -386, -734, -992, -957, -386, 685, 2288, 3939, 5158, 5012, 2930, -1853, -8888, -17283, -24782, -28312, -24422, -9825, 16674, 54197, 96584, 134729, 153718, 138624, 73438, -49526, -228614
Offset: 0

Views

Author

Seiichi Manyama, Apr 10 2017

Keywords

Crossrefs

Column k=2 of A276554.
Product_{k>0} (1-x^k)^(k*m): A161870 (m=-2), A073592 (m=1), this sequence (m=2), A276552 (m=3).

Formula

G.f.: Product_{k>0} (1-x^k)^(k*2).
G.f.: exp(-2*Sum_{k>=1} x^k/(k*(1 - x^k)^2)). - Ilya Gutkovskiy, May 30 2018

A026007 Expansion of Product_{m>=1} (1 + q^m)^m; number of partitions of n into distinct parts, where n different parts of size n are available.

Original entry on oeis.org

1, 1, 2, 5, 8, 16, 28, 49, 83, 142, 235, 385, 627, 1004, 1599, 2521, 3940, 6111, 9421, 14409, 21916, 33134, 49808, 74484, 110837, 164132, 241960, 355169, 519158, 755894, 1096411, 1584519, 2281926, 3275276, 4685731, 6682699, 9501979, 13471239, 19044780, 26850921, 37756561, 52955699
Offset: 0

Views

Author

Keywords

Comments

In general, for t > 0, if g.f. = Product_{m>=1} (1 + t*q^m)^m then a(n) ~ c^(1/6) * exp(3^(2/3) * c^(1/3) * n^(2/3) / 2) / (3^(2/3) * (t+1)^(1/12) * sqrt(2*Pi) * n^(2/3)), where c = Pi^2*log(t) + log(t)^3 - 6*polylog(3, -1/t). - Vaclav Kotesovec, Jan 04 2016

Examples

			For n = 4, we have 8 partitions
  01: [4]
  02: [4']
  03: [4'']
  04: [4''']
  05: [3, 1]
  06: [3', 1]
  07: [3'', 1]
  08: [2, 2']
		

Crossrefs

Programs

  • Maple
    with(numtheory):
    b:= proc(n) option remember;
          add((-1)^(n/d+1)*d^2, d=divisors(n))
        end:
    a:= proc(n) option remember;
          `if`(n=0, 1, add(b(k)*a(n-k), k=1..n)/n)
        end:
    seq(a(n), n=0..45);  # Alois P. Heinz, Aug 03 2013
  • Mathematica
    a[n_] := a[n] = 1/n*Sum[Sum[(-1)^(k/d+1)*d^2, {d, Divisors[k]}]*a[n-k], {k, 1, n}]; a[0] = 1; Table[a[n], {n, 0, 41}] (* Jean-François Alcover, Apr 17 2014, after Vladeta Jovovic *)
    nmax=50; CoefficientList[Series[Exp[Sum[(-1)^(k+1)*x^k/(k*(1-x^k)^2),{k,1,nmax}]],{x,0,nmax}],x] (* Vaclav Kotesovec, Feb 28 2015 *)
  • PARI
    N=66; q='q+O('q^N);
    gf= prod(n=1,N, (1+q^n)^n );
    Vec(gf)
    /* Joerg Arndt, Oct 06 2012 */

Formula

a(n) = (1/n)*Sum_{k=1..n} A078306(k)*a(n-k). - Vladeta Jovovic, Nov 22 2002
G.f.: Product_{m>=1} (1+x^m)^m. Weighout transform of natural numbers (A000027). Euler transform of A026741. - Franklin T. Adams-Watters, Mar 16 2006
a(n) ~ zeta(3)^(1/6) * exp((3/2)^(4/3) * zeta(3)^(1/3) * n^(2/3)) / (2^(3/4) * 3^(1/3) * sqrt(Pi) * n^(2/3)), where zeta(3) = A002117. - Vaclav Kotesovec, Mar 05 2015

A255528 G.f.: Product_{k>=1} 1/(1+x^k)^k.

Original entry on oeis.org

1, -1, -1, -2, 1, 0, 4, 2, 8, -2, 4, -11, -1, -25, -5, -35, 13, -26, 49, -6, 110, 6, 159, -23, 182, -141, 129, -358, 62, -640, 39, -897, 237, -1013, 771, -914, 1793, -664, 3143, -565, 4635, -1157, 5727, -3119, 6121, -7041, 5642, -13088, 5097, -20758, 5879
Offset: 0

Views

Author

Vaclav Kotesovec, Feb 24 2015

Keywords

Comments

In general, if m >= 1 and g.f. = Product_{k>=1} 1/(1 + x^k)^(m*k), then a(n, m) ~ (-1)^n * exp(-m/12 + 3 * 2^(-5/3) * m^(1/3) * Zeta(3)^(1/3) * n^(2/3)) * 2^(m/18 - 5/6) * A^m * m^(1/6 - m/36) * Zeta(3)^(1/6 - m/36) * n^(m/36 - 2/3) / sqrt(3*Pi), where A is the Glaisher-Kinkelin constant A074962. - Vaclav Kotesovec, Apr 13 2017

Crossrefs

Cf. A278710 (m=2), A279031 (m=3), A279411 (m=4), A279932 (m=5).

Programs

  • Maple
    with(numtheory): A000219:=proc(n) option remember; if n = 0 then 1 else add(sigma[2](k)*A000219(n-k), k = 1..n)/n fi: end: A073592:=proc(n) option remember; if n = 0 then 1 else -add(sigma[2](k)*A073592(n-k), k = 1..n)/n fi: end: a:=proc(n); add(A073592(n-2*m)*A000219(m), m = 0..floor(n/2)): end: seq(a(n), n = 0..50); # Vaclav Kotesovec, Mar 09 2015
  • Mathematica
    nmax=100; CoefficientList[Series[Product[1/(1+x^k)^k,{k,1,nmax}],{x,0,nmax}],x]
  • PARI
    {a(n) = if(n<0, 0, polcoeff(exp(sum(k=1, n, (-1)^k * x^k / (1-x^k)^2 / k, x*O(x^n))), n))}
    for(n=0, 100, print1(a(n), ", "))

Formula

a(n) ~ (-1)^n * A * Zeta(3)^(5/36) * exp(3*Zeta(3)^(1/3)*n^(2/3)/2^(5/3) - 1/12) / (2^(7/9) * sqrt(3*Pi) * n^(23/36)), where Zeta(3) = A002117 and A = A074962 is the Glaisher-Kinkelin constant. - Vaclav Kotesovec, Sep 29 2015
a(0) = 1, a(n) = -(1/n)*Sum_{k=1..n} A078306(k)*a(n-k) for n > 0. - Seiichi Manyama, Apr 06 2017

A283272 Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is expansion of Product_{j>=1} (1-x^j)^(j^k) in power of x.

Original entry on oeis.org

1, 1, -1, 1, -1, -1, 1, -1, -2, 0, 1, -1, -4, -1, 0, 1, -1, -8, -5, 0, 1, 1, -1, -16, -19, -1, 4, 0, 1, -1, -32, -65, -9, 21, 4, 1, 1, -1, -64, -211, -55, 127, 49, 7, 0, 1, -1, -128, -665, -285, 807, 500, 81, 3, 0, 1, -1, -256, -2059, -1351, 5179, 4809, 1038, 45
Offset: 0

Views

Author

Seiichi Manyama, Mar 04 2017

Keywords

Examples

			Square array begins:
   1,  1,  1,   1,   1,    1, ...
  -1, -1, -1,  -1,  -1,   -1, ...
  -1, -2, -4,  -8, -16,  -32, ...
   0, -1, -5, -19, -65, -211, ...
   0,  0, -1,  -9, -55, -285, ...
   1,  4, 21, 127, 807, 5179, ...
		

Crossrefs

Row k=5 gives A281581.
Main diagonal gives A283333.
Cf. A144048.

Formula

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

A283263 Expansion of exp( Sum_{n>=1} -sigma_3(n)*x^n/n ) in powers of x.

Original entry on oeis.org

1, -1, -4, -5, -1, 21, 49, 81, 45, -121, -484, -997, -1344, -840, 1624, 6931, 15149, 23155, 23469, 2240, -57596, -168929, -322587, -461165, -450668, -64135, 985621, 2935044, 5718865, 8597971, 9683008, 5596899, -8414092, -37295629, -83336988, -141108721
Offset: 0

Views

Author

Seiichi Manyama, Mar 04 2017

Keywords

Crossrefs

Column k=2 of A283272.
Cf. A023871 (exp( Sum_{n>=1} sigma_3(n)*x^n/n )).
Cf. exp( Sum_{n>=1} -sigma_k(n)*x^n/n ): A010815 (k=1), A073592 (k=2), this sequence (k=3), A283264 (k=4), A283271 (k=5).

Programs

  • Mathematica
    a[n_] := If[n<1, 1,-(1/n) * Sum[DivisorSigma[3, k] a[n - k], {k, n}]]; Table[a[n], {n, 0, 35}] (* Indranil Ghosh, Mar 16 2017 *)
  • PARI
    a(n) = if(n<1, 1, -(1/n) * sum(k=1, n, sigma(k, 3) * a(n - k)));
    for(n=0, 35, print1(a(n), ", ")) \\ Indranil Ghosh, Mar 16 2017
    
  • SageMath
    # uses[EulerTransform from A166861]
    b = EulerTransform(lambda n: -n^2)
    print([b(n) for n in range(36)]) # Peter Luschny, Nov 11 2020

Formula

G.f.: Product_{n>=1} (1 - x^n)^(n^2).
a(n) = -(1/n)*Sum_{k=1..n} sigma_3(k)*a(n-k).

A283271 Expansion of exp( Sum_{n>=1} -sigma_5(n)*x^n/n ) in powers of x.

Original entry on oeis.org

1, -1, -16, -65, -55, 807, 4809, 13135, 550, -169070, -862710, -2281174, -1221309, 20194565, 114391575, 346400092, 486546751, -1239516671, -11089537215, -41702958960, -93143227027, -45337210750, 674845109986, 3682196642725, 11405949184465, 20796945542222
Offset: 0

Views

Author

Seiichi Manyama, Mar 04 2017

Keywords

Comments

Let A(x) denote the g.f. and let m be an integer. Define a sequence by u(n) = [x^n] A(x)^(m*n). We conjecture that the supercongruence u(n*p^r) == u(n*p^(r-1)) (mod p^(3*r)) holds for all positive integers n and r and all primes p >= 7. Cf. A380581. - Peter Bala, Jan 21 2025

Crossrefs

Column k=4 of A283272.
Cf. A023873 (exp( Sum_{n>=1} sigma_5(n)*x^n/n )).
Cf. exp( Sum_{n>=1} -sigma_k(n)*x^n/n ): A010815 (k=1), A073592 (k=2), A283263 (k=3), A283264 (k=4), this sequence (k=5).

Formula

G.f.: Product_{n>=1} (1 - x^n)^(n^4).
a(n) = -(1/n)*Sum_{k=1..n} sigma_5(k)*a(n-k).

A283264 Expansion of exp( Sum_{n>=1} -sigma_4(n)*x^n/n ) in powers of x.

Original entry on oeis.org

1, -1, -8, -19, -9, 127, 500, 1038, 448, -4967, -21463, -50043, -59084, 70418, 600080, 1837349, 3532062, 3179251, -6965009, -42260393, -119597290, -224546234, -223670132, 292245783, 2156083245, 6428174973, 13030612271, 16820582355, -133402359, -78307103593
Offset: 0

Views

Author

Seiichi Manyama, Mar 04 2017

Keywords

Crossrefs

Column k=3 of A283272.
Cf. A023872 (exp( Sum_{n>=1} sigma_4(n)*x^n/n )).
Cf. exp( Sum_{n>=1} -sigma_k(n)*x^n/n ): A010815 (k=1), A073592 (k=2), A283263 (k=3), this sequence (k=4), A283271 (k=5).

Programs

  • SageMath
    # uses[EulerTransform from A166861]
    b = EulerTransform(lambda n: -n^3)
    print([b(n) for n in range(30)]) # Peter Luschny, Nov 11 2020

Formula

G.f.: Product_{n>=1} (1 - x^n)^(n^3).
a(n) = -(1/n)*Sum_{k=1..n} sigma_4(k)*a(n-k).

A276554 Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is the expansion of Product_{j>=1} (1-x^j)^(j*k) in powers of x.

Original entry on oeis.org

1, 1, 0, 1, -1, 0, 1, -2, -2, 0, 1, -3, -3, -1, 0, 1, -4, -3, 2, 0, 0, 1, -5, -2, 8, 6, 4, 0, 1, -6, 0, 16, 12, 12, 4, 0, 1, -7, 3, 25, 13, 9, 1, 7, 0, 1, -8, 7, 34, 5, -12, -29, -10, 3, 0, 1, -9, 12, 42, -15, -51, -78, -54, -32, -2, 0, 1, -10, 18, 48, -49, -102
Offset: 0

Views

Author

Seiichi Manyama, Apr 10 2017

Keywords

Examples

			Square array begins:
   1,  1,  1,  1,  1, ...
   0, -1, -2, -3, -4, ...
   0, -2, -3, -3, -2, ...
   0, -1,  2,  8, 16, ...
   0,  0,  6, 12, 13, ...
		

Crossrefs

Columns k=0-5 give: A000007, A073592, A276551, A276552, A316463, A316464.
Main diagonal gives A281267.
Antidiagonal sums give A299211.

Formula

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

A283336 Expansion of exp( Sum_{n>=1} -sigma_6(n)*x^n/n ) in powers of x.

Original entry on oeis.org

1, -1, -32, -211, -285, 5179, 44784, 162062, -125122, -5187417, -32587255, -95706881, 122837972, 3039216222, 17745876032, 52825817007, -24340390929, -1256623249600, -7805634068163, -26364952524572, -20649978457115, 368666542515083, 2777231006764690
Offset: 0

Views

Author

Seiichi Manyama, Mar 05 2017

Keywords

Crossrefs

Column k=5 of A283272.
Cf. A023874 (exp( Sum_{n>=1} sigma_6(n)*x^n/n )).
Cf. exp( Sum_{n>=1} -sigma_k(n)*x^n/n ): A010815 (k=1), A073592 (k=2), A283263 (k=3), A283264 (k=4), A283271 (k=5), this sequence (k=6), A283337 (k=7), A283338 (k=8), A283339 (k=9), A283340 (k=10).

Programs

  • Mathematica
    a[n_] := If[n<1, 1,-(1/n) * Sum[DivisorSigma[6, k] a[n - k], {k, n}]]; Table[a[n], {n, 0, 22}] (* Indranil Ghosh, Mar 16 2017 *)
  • PARI
    a(n) = if(n<1, 1, -(1/n) * sum(k=1, n, sigma(k, 6) * a(n - k)));
    for(n=0, 22, print1(a(n), ", ")) \\ Indranil Ghosh, Mar 16 2017

Formula

G.f.: Product_{n>=1} (1 - x^n)^(n^5).
a(n) = -(1/n)*Sum_{k=1..n} sigma_6(k)*a(n-k).

A283337 Expansion of exp( Sum_{n>=1} -sigma_7(n)*x^n/n ) in powers of x.

Original entry on oeis.org

1, -1, -64, -665, -1351, 33111, 408149, 1959491, -4502590, -149420286, -1182474566, -3678670450, 22384197409, 377982157035, 2474860645111, 6161653683590, -48899064011245, -695916857379611, -4275491639488601, -10750056317745704, 69316545348329853
Offset: 0

Views

Author

Seiichi Manyama, Mar 05 2017

Keywords

Crossrefs

Column k=6 of A283272.
Cf. A023875 (exp( Sum_{n>=1} sigma_7(n)*x^n/n )).
Cf. exp( Sum_{n>=1} -sigma_k(n)*x^n/n ): A010815 (k=1), A073592 (k=2), A283263 (k=3), A283264 (k=4), A283271 (k=5), A283336 (k=6), this sequence (k=7), A283338 (k=8), A283339 (k=9), A283340 (k=10).

Formula

G.f.: Product_{n>=1} (1 - x^n)^(n^6).
a(n) = -(1/n)*Sum_{k=1..n} sigma_7(k)*a(n-k).
Showing 1-10 of 35 results. Next