OFFSET
2,1
LINKS
Michael S. Branicky, Table of n, a(n) for n = 2..10001 (terms 2..1002 from Harry J. Smith)
FORMULA
a(n) = Min{sigma(c); p(n+1) > c > p(n)}, c is composite, p(n) is the n-th prime and sigma=A000203().
PROG
(PARI) { n=1; q=3; m=10^6; forprime (p=5, prime(1003), a=m; for (i=q + 1, p - 1, a=min(sigma(i), a)); q=p; write("b061120.txt", n++, " ", a) ) } \\ Harry J. Smith, Jul 18 2009
(Python)
from sympy import prime, divisor_sigma as sigma
def a(n): return min(sigma(c) for c in range(prime(n)+1, prime(n+1)))
print([a(n) for n in range(2, 58)]) # Michael S. Branicky, Jul 12 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, May 29 2001
EXTENSIONS
Offset changed by Michael S. Branicky, Jul 12 2021
STATUS
approved