login
A050264
Weak veryprimes.
1
2, 3, 5, 7, 11, 13, 17, 19, 23, 37, 43, 47, 53, 67, 73, 103, 107, 137, 157, 173, 227, 347, 487, 773
OFFSET
1,1
COMMENTS
No other terms less than 10^10 other than those stated above. - Robert G. Wilson v, Feb 10 2018
LINKS
Eric Weisstein's World of Mathematics, Veryprime
MATHEMATICA
veryprimeQ[n_] := Block[{p = 2}, While[p^2 <= n && 2 Abs[2 Mod[n, p] -p] <= p, p = NextPrime@ p]; p^2 > n]; Select[ Prime[ Range[140]], veryprimeQ](* Jean-François Alcover, Nov 30 2011 and slightly modified by Robert G. Wilson v, Feb 10 2018 *)
PROG
(Haskell)
a050264 n = a050264_list !! (n-1)
a050264_list = filter chi [2..] where
chi n = f a000040_list where
f (p:ps) | p*p > n = True
| otherwise = 2 * abs (2 * (n `mod` p) - p) <= p && f ps
-- Reinhard Zumkeller, Aug 11 2011
CROSSREFS
Sequence in context: A105581 A258433 A262363 * A075239 A255073 A341667
KEYWORD
nonn,nice
AUTHOR
Eric W. Weisstein, Jim Ferry (jferry(AT)uiuc.edu)
STATUS
approved