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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A211183 Triangle T(n,k), 0<=k<=n, read by rows, given by (0, 1, 1, 3, 3, 6, 6, 10, 10, 15, ...) DELTA (1, 0, 2, 0, 3, 0, 4, 0, 5, ...) where DELTA is the operator defined in A084938.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 2, 4, 1, 0, 7, 19, 11, 1, 0, 38, 123, 107, 26, 1, 0, 295, 1076, 1195, 474, 57, 1, 0, 3098, 12350, 16198, 8668, 1836, 120, 1, 0, 42271, 180729, 268015, 176091, 52831, 6549, 247, 1, 0, 726734, 3290353, 5369639, 4105015, 1564817, 287473, 22145
Offset: 0

Views

Author

Philippe Deléham, Feb 02 2013

Keywords

Examples

			Triangle begins :
1;
0, 1;
0, 1, 1;
0, 2, 4, 1;
0, 7, 19, 11, 1;
0, 38, 123, 107, 26, 1;
0, 295, 1076, 1195, 474, 57, 1;
0, 3098, 12350, 16198, 8668, 1836, 120, 1;
0, 42271, 180729, 268015, 176091, 52831, 6549, 247, 1;
0, 726734, 3290353, 5369639, 4105015, 1564817, 287473, 22145, 502, 1; ...
		

Crossrefs

Programs

  • PARI
    T(n,k)=polcoeff(polcoeff(sum(m=0, n, m!*x^m*prod(k=1, m, (y + (k-1)/2)/(1+(k*y+k*(k-1)/2)*x+x*O(x^n)))), n,x),k,y)
    for(n=0,12,for(k=0,n,print1(T(n,k),", "));print()) \\ Paul D. Hanna, Feb 03 2013

Formula

Sum_{k, 0<=k<=n}T(n,k)*x^(n-k) = A000012(n), A000366(n+1), A110501(n+1), A211194(n), A221972(n) for x = 0, 1, 2, 3, 4 respectively.
T(n,n-1) = A000295(n).
T(n,1) = A000366(n).
G.f.: A(x,y) = Sum_{n>=0} n! * x^n * Product_{k=1..n} (y + (k-1)/2) / (1 + (k*y + k*(k-1)/2)*x). - Paul D. Hanna, Feb 03 2013

A211194 G.f.: Sum_{n>=0} n! * (x/2)^n * Product_{k=1..n} (3*k-1) / (1 + k*(3*k-1)/2*x).

Original entry on oeis.org

1, 1, 4, 31, 394, 7441, 195544, 6822451, 305075254, 17010802021, 1157048302084, 94291964597671, 9069435785880514, 1016607721798423801, 131360503523334458224, 19382685928544981625691, 3239003918648541605116174, 608539911518928818091672781
Offset: 0

Views

Author

Paul D. Hanna, Feb 03 2013

Keywords

Comments

O.g.f. is related to pentagonal numbers A000326. If b(n) = A000326(n)*x/(1+A000326(n)x), we have A(x) = 1 +b(1) +b(1)b(2) +b(1)b(2)b(3) +b(1)b(2)b(3)b(4) + ... . Philippe Deléham, Feb 04 2013

Examples

			G.f.: A(x) = 1 + x + 5*x^2 + 49*x^3 + 797*x^4 + 19417*x^5 + 661829*x^6 +...
where
A(x) = 1 + 1*x/(1+x) + 1*5*x^2/((1+x)*(1+5*x)) + 1*5*12*x^3/((1+x)*(1+5*x)*(1+12*x)) + 1*5*12*22*x^4/((1+x)*(1+5*x)*(1+12*x)*(1+22*x)) + 1*5*12*22*35*x^5/((1+x)*(1+5*x)*(1+12*x)*(1+22*x)*(1+35*x)) + 1*5*12*22*35*51*x^6/((1+x)*(1+5*x)*(1+12*x)*(1+22*x)*(1+35*x)*(1+51*x)) +...
		

Crossrefs

Programs

  • PARI
    {a(n)=polcoeff(sum(m=0, n, m!*(x/2)^m*prod(k=1, m, (3*k-1)/(1+(3*k-1)/2*k*x+x*O(x^n)))), n)}
    for(n=0,21,print1(a(n),", "))

Formula

G.f.: Sum_{n>=0} A084939(n) * x^n / Product_{k=1..n} (1 + k*(3*k-1)/2*x).
a(n) = Sum_{k, 0<=k<=n} A211183(n,k)*3^(n-k). - Philippe Deléham, Feb 03 2013
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