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.

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A301306 G.f.: Sum_{n>=0} (1 + (1+x)^n)^n * x^n.

Original entry on oeis.org

1, 2, 5, 16, 60, 254, 1188, 6043, 33080, 193249, 1197001, 7819995, 53648847, 385090323, 2883045424, 22451716833, 181437812058, 1518374146260, 13133970646948, 117235109969112, 1078235776311405, 10204120439288725, 99244762587719585, 990878067150790140, 10145281310155565842, 106420501631411705747, 1142671059786354295966, 12548652816798990883431, 140839029768184796119004
Offset: 0

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Author

Paul D. Hanna, Mar 21 2018

Keywords

Examples

			G.f.: A(x) = 1 + 2*x + 5*x^2 + 16*x^3 + 60*x^4 + 254*x^5 + 1188*x^6 + 6043*x^7 + 33080*x^8 + 193249*x^9 + 1197001*x^10 + ...
such that
A(x) = 1 + (1 + (1+x))*x + (1 + (1+x)^2)^2*x^2 + (1 + (1+x)^3)^3*x^3 + (1 + (1+x)^4)^4*x^4 + (1 + (1+x)^5)^5*x^5 + (1 + (1+x)^6)^6*x^6 + ...
		

Crossrefs

Cf. A301465.

Programs

  • PARI
    {a(n) = my(A=1); A = sum(k=0,n, (1 + (1+x)^k +x*O(x^n))^k * x^k ); polcoeff(A,n)}
    for(n=0,30,print1(a(n),", "))
    
  • PARI
    {a(n) = sum(j=0,n, sum(k=0,n-j, binomial(n-j,k) * binomial((n-j)*k,j) ))}
    for(n=0,30,print1(a(n),", "))

Formula

G.f.: Sum_{n>=0} x^n * (1+x)^(n^2) / (1 - x*(1+x)^n)^(n+1).
G.f.: Sum_{n>=0} x^n * Sum_{k=0..n} binomial(n,k) * (1+x)^(n*k).
a(n) = Sum_{j=0..n} Sum_{k=0..n-j} binomial(n-j, k) * binomial((n-j)*k, j).

A301436 G.f. A(x) satisfies: 1 = Sum_{n>=0} ( 2*(1+x)^n - A(x) )^n / 2^(n+1).

Original entry on oeis.org

1, 6, 50, 1582, 82722, 5842550, 511261682, 52903385886, 6290859281538, 843328959011622, 125706002934030898, 20617322695573745742, 3689811206934015405474, 715633021826704924420758, 149544785675949258192968178, 33502338836970792659941911358, 8011296279710787237594088464898, 2036927238948023349890031708437830, 548778491694092921577420334962662962, 156179940994829385561873698156273034606
Offset: 0

Views

Author

Paul D. Hanna, Mar 24 2018

Keywords

Examples

			G.f.: A(x) = 1 + 6*x + 50*x^2 + 1582*x^3 + 82722*x^4 + 5842550*x^5 + 511261682*x^6 + 52903385886*x^7 + 6290859281538*x^8 + ...
such that
1 = 1/2  +  (2*(1+x) - A(x))/2^2  +  (2*(1+x)^2 - A(x))^2/2^3  +  (2*(1+x)^3 - A(x))^3/2^4  +  (2*(1+x)^4 - A(x))^4/2^5  +  (2*(1+x)^5 - A(x))^5/2^6 + ...
Also,
1 = 1/(2 + A(x))  +  2*(1+x)/(2 + (1+x)*A(x))^2  +  2^2*(1+x)^4/(2 + (1+x)^2*A(x))^3  +  2^3*(1+x)^9/(2 + (1+x)^3*A(x))^4  +  2^4*(1+x)^16/(2 + (1+x)^4*A(x))^5  +  2^5*(1+x)^25/(2 + (1+x)^5*A(x))^6  + ...
		

Crossrefs

Formula

G.f.: 1 = Sum_{n>=0} 2^n * (1+x)^(n^2) / (2 + (1+x)^n * A(x))^(n+1).
Showing 1-2 of 2 results.