A168343 n-th single or isolated number minus n.

1, 2, 3, 8, 13, 17, 23, 29, 33, 37, 42, 48, 54, 58, 64, 67, 72, 79, 83, 88, 92, 105, 108, 114, 125, 131, 136, 139, 144, 150, 161, 166, 178, 189, 193, 197, 203, 213, 218, 223, 229, 235, 239, 249, 262, 266, 270, 283, 288, 298, 302, 307, 314, 319, 324, 327, 332, 339

Offset: 1

Author

Juri-Stepan Gerasimov, Nov 23 2009

Keywords

• nonn

Programs

Maple

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: A167706 := proc(n) if n = 1 then 2; else for a from procname(n-1)+1 do if isA007510(a) or isA014574(a) then return(a) ; end if; end do ; end if; end proc: A168343 := proc(n) A167706(n)-n ; end proc: seq(A168343(n),n=1..80) ; # R. J. Mathar, Nov 24 2009

Formula

a(n) = A167706(n) - A000027(n) = A167706(n) - n.

Extensions

Corrected by R. J. Mathar, Nov 24 2009