A127752 Row sums of inverse of number triangle A(n,k) = 1/(3n+1) if k <= n <= 2k, 0 otherwise.
1, 4, 3, 7, 3, 6, 3, 10, 3, 6, 3, 9, 3, 6, 3, 13, 3, 6, 3, 9, 3, 6, 3, 12, 3, 6, 3, 9, 3, 6, 3, 16, 3, 6, 3, 9, 3, 6, 3, 12, 3, 6, 3, 9, 3, 6, 3, 15, 3, 6, 3, 9, 3, 6, 3, 12, 3, 6, 3, 9, 3, 6, 3, 19, 3, 6, 3, 9, 3, 6, 3, 12, 3, 6, 3, 9, 3, 6, 3, 15, 3, 6, 3, 9, 3, 6, 3, 12, 3, 6, 3, 9, 3, 6, 3, 18, 3, 6, 3, 9, 3, 6, 3, 12, 3, 6
Offset: 0
Keywords
Links
- Antti Karttunen, Table of n, a(n) for n = 0..2048
Programs
-
Mathematica
A[n_, k_] := If[k <= n <= 2k, 1/(3n+1), 0]; Total /@ Inverse[Array[A, {128, 128}, {0, 0}]] (* Jean-François Alcover, Feb 11 2021 *) -
PARI
up_to = 128; A127752aux(n,k) = if(k<=n,if(n<=(2*k),1/((3*n)+1),0),0); A127752list(up_to) = { my(m1=matrix(up_to,up_to,n,k,A127752aux(n-1,k-1)), m2 = matsolve(m1,matid(up_to)), v = vector(up_to)); for(n=1,up_to,v[n] = vecsum(m2[n,])); (v); }; v127752 = A127752list(1+up_to); A127752(n) = v127752[1+n]; \\ Antti Karttunen, Sep 29 2018
Extensions
More terms from Antti Karttunen, Sep 29 2018
Comments