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A050264 Weak veryprimes. 1

%I

%S 2,3,5,7,11,13,17,19,23,37,43,47,53,67,73,103,107,137,157,173,227,347,

%T 487,773

%N Weak veryprimes.

%C No other terms less than 10^10 other than those stated above. - _Robert G. Wilson v_, Feb 10 2018

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Veryprime.html">Veryprime</a>

%t 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-Fran├žois Alcover_, Nov 30 2011 and slightly modified by _Robert G. Wilson v_, Feb 10 2018 *)

%o (Haskell)

%o a050264 n = a050264_list !! (n-1)

%o a050264_list = filter chi [2..] where

%o chi n = f a000040_list where

%o f (p:ps) | p*p > n = True

%o | otherwise = 2 * abs (2 * (n `mod` p) - p) <= p && f ps

%o -- _Reinhard Zumkeller_, Aug 11 2011

%K nonn,nice

%O 1,1

%A _Eric W. Weisstein_, Jim Ferry (jferry(AT)uiuc.edu)

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Last modified June 18 06:56 EDT 2019. Contains 324203 sequences. (Running on oeis4.)