A167777 Even single (or even isolated) numbers.

2, 4, 6, 12, 18, 30, 42, 60, 72, 102, 108, 138, 150, 180, 192, 198, 228, 240, 270, 282, 312, 348, 420, 432, 462, 522, 570, 600, 618, 642, 660, 810, 822, 828, 858, 882, 1020, 1032, 1050, 1062, 1092, 1152, 1230, 1278, 1290, 1302, 1320, 1428, 1452, 1482, 1488

Offset

1,1

Comments

Two together with average of twin prime pairs.

Links

Table of n, a(n) for n=1..51.

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

Cf. A014574 (average of twin prime pairs), A167706 (the single or isolated numbers).

Sequence in context: A192096 A181740 A192224 * A259941 A007436 A052847

Adjacent sequences: A167774 A167775 A167776 * A167778 A167779 A167780

Keyword

nonn

Author

Juri-Stepan Gerasimov, Nov 11 2009

Status

approved