OFFSET
4,1
COMMENTS
LINKS
P. CAMI, Table of n, a(n) for n = 4..60000
FORMULA
a(n) = 2n - A078496(n)
MATHEMATICA
Table[p=n+1; q=2n-p; While[q>0&&!(PrimeQ[p]&&PrimeQ[q]), p++; q-- ]; q, {n, 4, 100}]
PROG
(PARI) a(n) = {my(p = precprime(n-1)); while(!isprime(2*n-p), p = precprime(p-1)); p; } \\ Michel Marcus, Oct 22 2016
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
T. D. Noe, Dec 02 2002
EXTENSIONS
STATUS
approved