A209424 Triangle defined by g.f.: A(x,y) = exp( Sum_{n>=1} x^n/n * Sum_{k=0..n} binomial(n, k)^n * y^k ), as read by rows.
1, 1, 1, 1, 3, 1, 1, 12, 12, 1, 1, 76, 347, 76, 1, 1, 701, 20429, 20429, 701, 1, 1, 8477, 1919660, 10707908, 1919660, 8477, 1, 1, 126126, 259227625, 9203978774, 9203978774, 259227625, 126126, 1, 1, 2223278, 47484618291, 12099129236936, 72078431500368
Offset: 0
Examples
This triangle begins: 1; 1, 1; 1, 3, 1; 1, 12, 12, 1; 1, 76, 347, 76, 1; 1, 701, 20429, 20429, 701, 1; 1, 8477, 1919660, 10707908, 1919660, 8477, 1; 1, 126126, 259227625, 9203978774, 9203978774, 259227625, 126126, 1; 1, 2223278, 47484618291, 12099129236936, 72078431500368, 12099129236936, 47484618291, 2223278, 1; ... G.f.: A(x,y) = 1 + (1+y)*x + (1+3*y+y^2)*x^2 + (1+12*y+12*y^2+y^3)*x^3 + (1+76*y+20429*y^2+76*y^3+y^4)*x^4 +... The logarithm of the g.f. equals the series: log(A(x,y)) = (1 + y)*x + (1 + 2^2*y + y^2)*x^2/2 + (1 + 3^3*y + 3^3*y^2 + y^3)*x^3/3 + (1 + 4^4*y + 6^4*y^2 + 4^4*y^3 + y^4)*x^4/4 + (1 + 5^5*y + 10^5*y^2 + 10^5*y^3 + 5^5*y^4 + y^5)*x^5/5 +... in which the coefficients are found in triangle A209427.
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Programs
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PARI
{T(n,k)=polcoeff(polcoeff(exp(sum(m=1,n,x^m/m*sum(k=0,m,binomial(m,k)^m*y^k))+x*O(x^n)),n,x),k,y)} for(n=0,10,for(k=0,n,print1(T(n,k),", "));print(""))
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