A104448 Row sums of triangle A104446.

1, 3, 6, 13, 33, 101, 372, 1624, 8263, 48285, 320031, 2380114, 19675986, 179314868, 1788473424, 19398149629, 227510745445, 2871040422932, 38810001746171, 559745948482030, 8582882169611759, 139467832061599433

Offset: 0

Author

Paul D. Hanna, Mar 08 2005

Keywords

• nonn

Comments

A104446 equals the square of triangular matrix A104445, read by rows, where X=[A104445] satisfies: SHIFT_LEFT_UP(X) = X^2 - X + I.

Crossrefs

Cf. A104446, A104445, A091352, A091351.

Programs

PARI

a(n)=local(A=Mat(1),B);for(m=1,n+1,B=A^2-A+A^0; A=matrix(m+1,m+1);for(i=1,m+1, for(j=1,i, if(i<2 || j==i,A[i,j]=1,if(j==1,A[i,j]=1,A[i,j]=B[i-1,j-1]))))); return(sum(k=1,n+1,(A^2)[n+1,k]))

Formula

a(n) = A091352(n) + A091352(n-1) for n>0.