OFFSET
1,17
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
For n = 7, the a(7) = 1 solution is 2*7 = 3 + 11 = 7 + 7; one of these pairs, 3 + 11, contains a number less than sqrt(2*7 - 2).
MAPLE
P:= NULL: A[1]:= 0: nextp:= 2:
for n from 2 to 100 do
while nextp^2 < 2*n-2 do
P:= P, nextp;
nextp:= nextprime(nextp);
od;
A[n]:= numboccur(true, map(t -> isprime(2*n-t), [P]))
od:
seq(A[i], i=1..100); # Robert Israel, Apr 30 2019
PROG
(PARI)
a(n)=sum(i=2, primepi(floor(sqrt(2*n-2))), isprime(2*n-prime(i))) \\ Lear Young, Apr 11 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Lear Young, Apr 11 2014
STATUS
approved