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A163083 Primes of the form k$ + 1 which are the greater of twin primes. Here '$' denotes the swinging factorial function (A056040). 3
7, 31, 51481, 1580132580471901 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Subsequence of A163075 and of A006512.
LINKS
Peter Luschny, Swinging Primes.
MAPLE
a := proc(n) select(s->isprime(s) and isprime(s-2), map(k -> A056040(k)+1, [$4..n])) end:
MATHEMATICA
sf[n_] := With[{f = Floor[n/2]}, Pochhammer[f+1, n-f]/f!]; Do[ If[ PrimeQ[p = sf[n] + 1] && PrimeQ[p - 2], Print["n = ", n, " p = ", p]], {n, 1, 400}] (* Jean-François Alcover, Jul 29 2013 *)
CROSSREFS
Sequence in context: A134709 A139314 A290969 * A101329 A193637 A214490
KEYWORD
nonn
AUTHOR
Peter Luschny, Jul 21 2009
STATUS
approved

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Last modified February 24 22:04 EST 2024. Contains 370307 sequences. (Running on oeis4.)