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A167394
Largest single or isolated prime < n-th single or isolated composite.
1
2, 2, 2, 2, 23, 37, 53, 67, 97, 97, 131, 131, 173, 173, 173, 223, 233, 263, 277, 307, 337, 409, 409, 457, 509, 563, 593, 613, 631, 653, 797, 797, 797, 853, 877, 1013, 1013, 1039, 1039, 1087, 1129, 1223, 1259, 1283, 1297, 1307, 1423, 1447, 1471, 1471, 1601, 1613
OFFSET
1,1
MAPLE
isA007510 := proc(n) isprime(n) and not isprime(n+2) and not isprime(n-2) ; simplify(%) ; end proc:
A167394 := proc(n) local a; for a from A014574(n)-1 by -1 do if isA007510(a) then return a; end if; end do: end proc:
seq(A167394(n), n=1..120) ; # R. J. Mathar, May 30 2010
CROSSREFS
Sequence in context: A067096 A259704 A249779 * A029627 A075182 A292023
KEYWORD
nonn
AUTHOR
EXTENSIONS
Corrected (47 replaced with 53, 211 replaced with 223, etc.) by R. J. Mathar, May 30 2010
STATUS
approved