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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A257532 Triangle, read by rows, T(n,k)=k/n*Sum_{i=0..n-k} C(2*n,n-k-i)*C(2*n+i-1,i).

Original entry on oeis.org

1, 4, 1, 24, 8, 1, 172, 64, 12, 1, 1360, 536, 120, 16, 1, 11444, 4672, 1156, 192, 20, 1, 100520, 42024, 11088, 2096, 280, 24, 1, 911068, 387456, 106908, 22016, 3420, 384, 28, 1, 8457504, 3643448, 1038984, 227408, 39120, 5192, 504, 32, 1
Offset: 1

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Author

Vladimir Kruchinin, Apr 28 2015

Keywords

Examples

			1;
4, 1;
24, 8, 1;
172, 64, 12, 1;
1360, 536, 120, 16, 1;
		

Crossrefs

Cf. A027307. First column = A032349.

Programs

  • Maxima
    T(n,k):=(k*sum(binomial(2*n,n-k-i)*binomial(2*n+i-1,i),i,0,n-k))/n;

Formula

G.f.: 1/(1-x*B(x)^2*y)-1, where B(x) is g.f. of A027307.
G.f. satisfies A(x)=x*[(1+A(x))/(1-A(x))]^2.

A305537 G.f. A(x) satisfies: A(x) = 1/(1 - x*A(x) - x*A(x)/(1 - x*A(x) - 2*x*A(x)/(1 - x*A(x) - 3*x*A(x)/(1 - x*A(x) - 4*x*A(x)/(1 - ...))))), a continued fraction.

Original entry on oeis.org

1, 2, 11, 87, 844, 9438, 118217, 1636078, 24869591, 414422424, 7568815758, 151468591827, 3317061005044, 79265498450882, 2058189152006115, 57777549430984983, 1744191365957251044, 56332730020388347302, 1937412176139535240463, 70659708678402399722656
Offset: 0

Views

Author

Ilya Gutkovskiy, Jun 04 2018

Keywords

Examples

			G.f. A(x) = 1 + 2*x + 11*x^2 + 87*x^3 + 844*x^4 + 9438*x^5 + 118217*x^6 + 1636078*x^7 + 24869591*x^8 + ...
		

Crossrefs

Formula

a(n) = [x^n] (Sum_{k>=0} A001515(k)*x^k)^(n+1)/(n + 1).
Previous Showing 71-72 of 72 results.