OFFSET
1,1
EXAMPLE
For n=1, c(1)= 4, p(1)= 2; c(2) + p(4) = 6 + 7 = 13 (prime).
For n=2, c(2)= 6, p(2)= 3; c(3) + p(6) = 8 + 13 = 21 = a(1).
For n=3, c(3)= 8, p(3)= 5; c(5) + p(8) = 10 + 19 = 29 (prime).
For n=4, c(4)= 9, p(4)= 7; c(7) + p(9) = 14 + 23 = 37 (prime).
For n=5, c(5)=10, p(5)=11; c(11) + p(10) = 20 + 29 = 49 = a(2).
For n=6, c(6)=12, p(6)=13; c(13) + p(12) = 22 + 37 = 59 (prime).
For n=7, c(7)=14, p(7)=17; c(17) + p(14) = 27 + 43 = 70 = a(3).
PROG
(PARI) p(n) = prime(n); \\ A000040
c(n) = for(k=0, primepi(n), isprime(n++)&&k--); n; \\ A002808
select(x->(!isprime(x)), vector(70, n, c(p(n)) + p(c(n)))) \\ Michel Marcus, Jan 29 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Aug 14 2008
EXTENSIONS
Edited and corrected by Ray Chandler, Aug 19 2008
STATUS
approved