OFFSET
2,1
COMMENTS
For n>1, a(n) is a lower bound for A219787(n). - Michel Marcus , Nov 28 2012.
LINKS
P. Erdos and C. Pomerance, Matching the natural numbers up to n with distinct multiples in another interval, Nederl. Akad. Wetensch. Proc. Ser. A 83 (1980), 147-161.
EXAMPLE
For n=4, a(n)=9 as there are 3 composite numbers between 5 and 9: 6, 8, and 9.
For n=11, a(n)= 25 with the 11 composite numbers: 12, 14, 15, 16, 18, 20, 21, 22, 24, 25 (cf comment in A219787).
PROG
(PARI) a(n) = {nbc = 0; nn = n+1; while (nbc != n-1, if (! isprime(nn), nbc++; ); if (nbc != n-1, nn++); ); return (nn); }
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Marcus, Nov 28 2012
STATUS
approved