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A167777 Even single (or even isolated) numbers. 2
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified October 25 20:21 EDT 2021. Contains 348256 sequences. (Running on oeis4.)