A050264 Weak veryprimes.

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

Table of n, a(n) for n=1..24.

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

Adjacent sequences: A050261 A050262 A050263 * A050265 A050266 A050267

Keyword

nonn,nice

Author

Eric W. Weisstein, Jim Ferry (jferry(AT)uiuc.edu)

Status

approved