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.

A249480 E.g.f.: A(x,y) = exp(y)*P(x) - Q(x,y), where P(x) = 1/Product_{n>=1} (1 - x^n/n) and Q(x,y) = Sum_{n>=1} y^n / Product_{k=1..n} (k - x^k).

Original entry on oeis.org

1, 1, 0, 3, 1, 0, 11, 5, 1, 0, 56, 32, 7, 1, 0, 324, 204, 57, 9, 1, 0, 2324, 1604, 487, 89, 11, 1, 0, 18332, 13292, 4441, 897, 128, 13, 1, 0, 167544, 127224, 44712, 9864, 1486, 174, 15, 1, 0, 1674264, 1311384, 485592, 111744, 18486, 2286, 227, 17, 1, 0, 18615432, 14986632, 5735616, 1393872, 240318, 31734, 3329, 287, 19, 1, 0
Offset: 0

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Author

Paul D. Hanna, Nov 02 2014

Keywords

Comments

The function P(x) = Product_{n>=1} 1/(1 - x^n/n) equals the e.g.f. of A007841, the number of factorizations of permutations of n letters into cycles in nondecreasing length order.

Examples

			 Triangle begins:
1;
1, 0;
3, 1, 0;
11, 5, 1, 0;
56, 32, 7, 1, 0;
324, 204, 57, 9, 1, 0;
2324, 1604, 487, 89, 11, 1, 0;
18332, 13292, 4441, 897, 128, 13, 1, 0;
167544, 127224, 44712, 9864, 1486, 174, 15, 1, 0;
1674264, 1311384, 485592, 111744, 18486, 2286, 227, 17, 1, 0;
18615432, 14986632, 5735616, 1393872, 240318, 31734, 3329, 287, 19, 1, 0;
223686792, 183769992, 72550296, 18223632, 3296958, 455742, 51009, 4647, 354, 21, 1, 0;
2937715296, 2458713696, 993598248, 257587416, 48076704, 6958656, 801880, 77896, 6272, 428, 23, 1, 0;
41233157952, 35006137152, 14438206776, 3835359192, 738870048, 110022696, 13300084, 1330300, 114164, 8236, 509, 25, 1, 0; ...
GENERATING FUNCTION.
G.f.: A(x,y) = 1 + (1)*x + (3 + y)*x^2/2! + (11 + 5*y + y^2)*x^3/3! +
(56 + 32*y + 7*y^2 + y^3)*x^4/4! +
(324 + 204*y + 57*y^2 + 9*y^3 + y^4)*x^5/5! +
(2324 + 1604*y + 487*y^2 + 89*y^3 + 11*y^4 + y^5)*x^6/6! +...
such that
A(x,y) = exp(y)*P(x) - Q(x,y)
where
P(x) = 1/Product_{n>=1} (1 - x^n/n) = Sum_{n>=0} A007841(n)*x^n/n!, and
Q(x,y) = Sum_{n>=1} y^n / Product_{k=1..n} (k - x^k).
More explicitly,
P(x) = 1/((1-x)*(1-x^2/2)*(1-x^3/3)*(1-x^4/4)*(1-x^5/5)*...)
Q(x,y) = y/(1-x) + y^2/((1-x)*(2-x^2)) + y^3/((1-x)*(2-x^2)*(3-x^3)) + y^4/((1-x)*(2-x^2)*(3-x^3)*(4-x^4)) + y^5/((1-x)*(2-x^2)*(3-x^3)*(4-x^4)*(5-x^5)) +...
Column zero of this triangle forms the e.g.f. of A007841:
P(x) = 1 + x + 3*x^2/2! + 11*x^3/3! + 56*x^4/4! + 324*x^5/5! + 2324*x^6/6! + 18332*x^7/7! + 167544*x^8/8! +...
		

Crossrefs

Programs

  • PARI
    {T(n,k)=local(A=1, P=((prod(j=1, n+1, 1/(1 - x^j/j +x^2*O(x^n))))),
    Q=((sum(m=1, n+1, y^m * prod(j=1, m, 1/(j - x^j +x^2*O(x^n)))))) );
    A=exp(y)*P - Q; n!*polcoeff(polcoeff(A,n,x),k,y)}
    for(n=0,12,for(k=0,n,print1(T(n,k),", "));print(""))