A081523 Sum of terms in row n of A081521.

1, 4, 12, 16, 20, 54, 35, 64, 72, 130, 77

Offset: 1

Author

Amarnath Murthy, Mar 27 2003

Keywords

• nonn
• more

Crossrefs

Cf. A081521, A081522, A081524.

Programs

PARI

a(n) = {my(m=n*(n-1)/2, v); forstep(k=m+n/(2-n%2), oo, n, v=List([]); for(i=2, k-m, if(gcd(n, i)==1, listput(v, i))); if(#v>n-2, forsubset([#v, n-1], w, if(r=1+sum(i=1, n-1, v[w[i]])==k, return(k))))); } \\ Jinyuan Wang, May 23 2020

Extensions

a(8)-a(11) from Jinyuan Wang, May 23 2020