A085428 Sum of the smallest and largest prime divisors of the n-th composite number.

4, 5, 4, 6, 7, 5, 9, 8, 4, 5, 7, 10, 13, 5, 10, 15, 6, 9, 7, 4, 14, 19, 12, 5, 21, 16, 7, 9, 13, 8, 25, 5, 14, 7, 20, 15, 5, 16, 9, 22, 31, 7, 33, 10, 4, 18, 13, 19, 26, 9, 5, 39, 8, 21, 18, 15, 7, 6, 43, 9, 22, 45, 32, 13, 7, 20, 25, 34, 49, 24, 5, 9, 14, 7

Offset

0,1

Links

Table of n, a(n) for n=0..73.

Prog

(PARI) maxpmindivc(n) = { for(x=4, n, s=0; forstep(p=2, x-1, 1, if(x%p==0 & isprime(p), s=p; break); ); forstep(p=x-1, 2, -1, if(x%p==0 & isprime(p), print1(s+p, ", "); break); ) ) }

Crossrefs

Equals A056608(n) + A052369(n).

Sequence in context: A198817 A248624 A363195 * A053025 A010664 A074967

Adjacent sequences: A085425 A085426 A085427 * A085429 A085430 A085431

Keyword

easy,nonn

Author

Cino Hilliard, Aug 13 2003

Status

approved