A081517 Consider the smallest number m which can be expressed as the sum of n distinct numbers coprime to m. Sequence gives triangle (read by rows) of the set of coprime numbers pertaining to m. When there is a choice, use the lexicographically earliest solution.

1, 1, 2, 1, 2, 4, 1, 2, 3, 5, 1, 2, 3, 4, 7, 1, 2, 3, 4, 5, 8, 1, 2, 3, 4, 5, 6, 8, 1, 2, 3, 4, 5, 6, 7, 9, 1, 2, 3, 4, 5, 6, 7, 8, 11, 1, 2, 3, 4, 5, 6, 7, 8, 9, 14, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 19

Offset

1,3

Links

Table of n, a(n) for n=1..91.

Example

Triangle begins:
1;
1,2;
1,2,4;
1,2,3,5;
1,2,3,4,7;
1,2,3,4,5,8;

Prog

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

Crossrefs

Cf. A081515, A081516.

Sequence in context: A300792 A132082 A129644 * A104778 A356184 A292477

Adjacent sequences: A081514 A081515 A081516 * A081518 A081519 A081520

Keyword

nonn,tabl

Author

Amarnath Murthy, Mar 27 2003

Extensions

More terms from R. J. Mathar, Mar 23 2007

More terms from Jinyuan Wang, May 23 2020

Status

approved