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 14 results. Next

A283333 Main diagonal of A283272.

Original entry on oeis.org

1, -1, -4, -19, -55, 5179, 408149, 23366098, -2659962750, -2946880278857, -1715161696081878, 603927037021100215, 9904716216487281046207, 52286804207990141325901614, -71925062774291844591785748425, -17522340813140430159774329947096591
Offset: 0

Views

Author

Seiichi Manyama, Mar 04 2017

Keywords

Crossrefs

Cf. A283272.

Programs

  • Ruby
    require 'prime'
    def power(a, n)
      return 1 if n == 0
      k = power(a, n >> 1)
      k *= k
      return k if n & 1 == 0
      return k * a
    end
    def sigma(x, i)
      sum = 1
      pq = i.prime_division
      if x == 0
        pq.each{|a, n| sum *= n + 1}
      else
        pq.each{|a, n| sum *= (power(a, (n + 1) * x) - 1) / (power(a, x) - 1)}
      end
      sum
    end
    def A(k, m, n)
      ary = [1]
      s_ary = [0] + (1..n).map{|i| sigma(k, i * m)}
      (1..n).each{|i| ary << (1..i).inject(0){|s, j| s - ary[-j] * s_ary[j]} / i}
      ary
    end
    def A283333(n)
      (0..n).map{|i| A(i + 1, 1, i)[-1]}
    end

Formula

a(n) = [x^n] Product_{k=1..n} (1 - x^k)^(k^n). - Ilya Gutkovskiy, Mar 06 2018

A073592 Euler transform of negative integers.

Original entry on oeis.org

1, -1, -2, -1, 0, 4, 4, 7, 3, -2, -9, -17, -25, -24, -13, -1, 32, 61, 97, 111, 112, 74, 8, -108, -243, -392, -512, -569, -542, -358, -33, 473, 1078, 1788, 2395, 2865, 2955, 2569, 1496, -245, -2751, -5783, -9121, -12299, -14739, -15806, -14719, -10930, -3813, 6593, 20284, 36139, 53081, 68620, 80539
Offset: 0

Views

Author

Vladeta Jovovic, Aug 28 2002

Keywords

Comments

1/A(x) is g.f. for A000219.

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; `if`(n=0, 1, -add(
          numtheory[sigma][2](j)*a(n-j), j=1..n)/n)
        end:
    seq(a(n), n=0..60);  # Alois P. Heinz, Mar 12 2015
  • Mathematica
    nmax=50; CoefficientList[Series[Exp[Sum[-x^k/(k*(1-x^k)^2),{k,1,nmax}]],{x,0,nmax}],x] (* Vaclav Kotesovec, Mar 02 2015 *)
    a[n_]:= a[n] = -1/n*Sum[DivisorSigma[2,k]*a[n-k],{k,1,n}]; a[0]=1; Table[a[n],{n,0,100}] (* Vaclav Kotesovec, Mar 02 2015 *)
  • SageMath
    # uses[EulerTransform from A166861]
    b = EulerTransform(lambda n: -n)
    print([b(n) for n in range(55)]) # Peter Luschny, Nov 11 2020

Formula

G.f.: Product_{k>0} (1-x^k)^k.
a(n) = -1/n*Sum_{k=1..n} sigma[2](k)*a(n-k).
G.f.: exp( Sum_{n>=1} -sigma_2(n)*x^n/n ). - Seiichi Manyama, Mar 04 2017

A144048 Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is Euler transform of (j->j^k).

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 5, 6, 5, 1, 1, 9, 14, 13, 7, 1, 1, 17, 36, 40, 24, 11, 1, 1, 33, 98, 136, 101, 48, 15, 1, 1, 65, 276, 490, 477, 266, 86, 22, 1, 1, 129, 794, 1828, 2411, 1703, 649, 160, 30, 1, 1, 257, 2316, 6970, 12729, 11940, 5746, 1593, 282, 42, 1, 1, 513
Offset: 0

Views

Author

Alois P. Heinz, Sep 08 2008

Keywords

Comments

In general, column k > 0 is asymptotic to (Gamma(k+2)*Zeta(k+2))^((1-2*Zeta(-k)) /(2*k+4)) * exp((k+2)/(k+1) * (Gamma(k+2)*Zeta(k+2))^(1/(k+2)) * n^((k+1)/(k+2)) + Zeta'(-k)) / (sqrt(2*Pi*(k+2)) * n^((k+3-2*Zeta(-k))/(2*k+4))). - Vaclav Kotesovec, Mar 01 2015

Examples

			Square array begins:
  1,  1,   1,   1,    1,     1, ...
  1,  1,   1,   1,    1,     1, ...
  2,  3,   5,   9,   17,    33, ...
  3,  6,  14,  36,   98,   276, ...
  5, 13,  40, 136,  490,  1828, ...
  7, 24, 101, 477, 2411, 12729, ...
		

Crossrefs

Rows give: 0-1: A000012, 2: A000051, A094373, 3: A001550, 4: A283456, 5: A283457.
Main diagonal gives A252782.
Cf. A283272.

Programs

  • Maple
    with(numtheory): etr:= proc(p) local b; b:= proc(n) option remember; `if`(n=0,1, add(add(d*p(d), d=divisors(j)) *b(n-j), j=1..n)/n) end end: A:= (n,k)-> etr(j->j^k)(n); seq(seq(A(n,d-n), n=0..d), d=0..13);
  • Mathematica
    etr[p_] := Module[{ b}, b[n_] := b[n] = If[n == 0, 1, Sum[Sum[d*p[d], {d, Divisors[j]}]*b[n - j], {j, 1, n}]/n]; b]; A[n_, k_] := etr[Function[j, j^k]][n]; Table[Table[A[n, d - n], {n, 0, d}], {d, 0, 13}] // Flatten (* Jean-François Alcover, Dec 27 2013, translated from Maple *)

Formula

G.f. of column k: Product_{j>=1} 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).

A284992 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, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 4, 5, 2, 1, 1, 8, 13, 8, 3, 1, 1, 16, 35, 31, 16, 4, 1, 1, 32, 97, 119, 83, 28, 5, 1, 1, 64, 275, 457, 433, 201, 49, 6, 1, 1, 128, 793, 1763, 2297, 1476, 487, 83, 8, 1, 1, 256, 2315, 6841, 12421, 11113, 4962, 1141, 142, 10, 1, 1
Offset: 0

Views

Author

Seiichi Manyama, Apr 07 2017

Keywords

Examples

			Square array begins:
  1,  1,   1,    1,     1,      1,       1,        1, ...
  1,  1,   1,    1,     1,      1,       1,        1, ...
  1,  2,   4,    8,    16,     32,      64,      128, ...
  2,  5,  13,   35,    97,    275,     793,     2315, ...
  2,  8,  31,  119,   457,   1763,    6841,    26699, ...
  3, 16,  83,  433,  2297,  12421,   68393,   382573, ...
  4, 28, 201, 1476, 11113,  85808,  678101,  5466916, ...
  5, 49, 487, 4962, 52049, 561074, 6189117, 69540142, ...
		

Crossrefs

Columns k=0-5 give A000009, A026007, A027998, A248882, A248883, A248884.
Rows (0+1),2-3 give: A000012, A000079, A007689.
Main diagonal gives A270917.

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)*binomial(i^k, j), j=0..n/i)))
        end:
    A:= (n, k)-> b(n$2, k):
    seq(seq(A(n, d-n), n=0..d), d=0..14);  # Alois P. Heinz, Oct 16 2017
  • 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]*Binomial[i^k, j], {j, 0, n/i}]]];
    A[n_, k_] := b[n, n, k];
    Table[Table[A[n, d - n], {n, 0, d}], {d, 0, 14}] // Flatten (* Jean-François Alcover, Feb 10 2021, after Alois P. Heinz *)

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).

A283338 Expansion of exp( Sum_{n>=1} -sigma_8(n)*x^n/n ) in powers of x.

Original entry on oeis.org

1, -1, -128, -2059, -6069, 210067, 3664420, 23366098, -116899962, -4133365357, -41809923367, -125160180169, 2447495850838, 42931762306584, 321967686614676, 281683012498569, -23874414003295851, -318729240693402530, -1992572289343189863
Offset: 0

Views

Author

Seiichi Manyama, Mar 05 2017

Keywords

Crossrefs

Column k=7 of A283272.
Cf. A023876 (exp( Sum_{n>=1} sigma_8(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), A283337 (k=7), this sequence (k=8), A283339 (k=9), A283340 (k=10).

Formula

G.f.: Product_{n>=1} (1 - x^n)^(n^7).
a(n) = -(1/n)*Sum_{k=1..n} sigma_8(k)*a(n-k).
Showing 1-10 of 14 results. Next