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First nonprime number reached when iterating n under x->2*x+1.
3

%I #15 Jul 22 2023 17:39:05

%S 1,95,15,4,95,6,15,8,9,10,95,12,27,14,15,16,35,18,39,20,21,22,95,24,

%T 25,26,27,28,119,30,63,32,33,34,35,36,75,38,39,40,335,42,87,44,45,46,

%U 95,48,49,50,51,52,215,54,55,56,57,58,119,60,123,62,63,64,65,66,135

%N First nonprime number reached when iterating n under x->2*x+1.

%H Amiram Eldar, <a href="/A093007/b093007.txt">Table of n, a(n) for n = 1..10000</a>

%F n>1: A070939(a(n)) = A070939(n) + A063377(n), A000120(a(n)) = A000120(n) + A063377(n).

%e n = 41 = A000040(13) -> 2*41+1 = 83 = A000040(23) -> 2*83+1 = 167 = A000040(39) -> 2*167+1 = 335 = 67*5, therefore a(41) = 335, A063377(41) = 3.

%t Table[NestWhile[2#+1&,n,PrimeQ],{n,70}] (* _Harvey P. Dale_, Sep 25 2012 *)

%Y Cf. A000040, A000120, A038699, A063377, A070939, A093009.

%K nonn

%O 1,2

%A _Reinhard Zumkeller_, Mar 14 2004

%E Definition corrected by _Harvey P. Dale_, Sep 25 2012