OFFSET
1,1
COMMENTS
Two together with average of twin prime pairs.
MAPLE
Contribution from R. J. Mathar, Apr 14 2010: (Start)
isA007510 := proc(n) if isprime(n) then not isprime(n+2) and not isprime(n-2) ; else false; end if; end proc:
isA014574 := proc(n) if not isprime(n) then isprime(n+1) and isprime(n-1) ; else false; end if; end proc:
A167777 := proc(n) if n = 1 then 2; else for a from procname(n-1)+2 by 2 do if isA007510(a) or isA014574(a) then return(a) ; end if; end do ; end if; end proc:
seq(A167777(n), n=1..60) ; (End)
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Nov 11 2009
STATUS
approved