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%I #27 Sep 08 2022 08:45:39
%S 0,2,5,8,9,11,12,14,16,17,20,22,23,26,29,30,32,34,35,36,37,38,39,41,
%T 44,45,47,48,50,51,53,55,56,58,59,61,62,65,67,68,71,72,73,74,77,78,79,
%U 80,83,84,85,86,87,89,90,92,93,95,96,98,100,101,104,107,108,110
%N Numbers n such that 10*n+1 is not prime.
%C Multiplied by 2 we have 4,10,16,18,... which is the set of even terms of A153329. - _R. J. Mathar_, Jan 23 2009
%H Vincenzo Librandi, <a href="/A153275/b153275.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) = (A053178(n)-1)/10. - _R. J. Mathar_, Oct 30 2009
%e Distribution of the terms in the following triangular array:
%e *;
%e *,*;
%e 2,*,*;
%e *,*,*,8;
%e *,*,*,*,12;
%e *,*,9,*,*,*;
%e *,*,*,*,*,*,*;
%e 5,*,*,*,*,22,*,*;
%e *,*,*,17,*,*,*,*,36;
%e *,*,*,*,23,*,*,*,*,44;
%e *,*,16,*,*,*,*,39,*,*,*; etc.
%e where * marks the non-integer values of (2*h*k + k + h)/5 with h >= k >= 1. - _Vincenzo Librandi_, Jan 15 2013
%p q:= n-> not isprime(10*n+1):
%p select(q, [$0..120])[]; # _Alois P. Heinz_, Jan 21 2021
%t Select[Range[0, 200], !PrimeQ[10*# + 1]&] (* _Vincenzo Librandi_, Jan 12 2013 *)
%o (Magma) [n: n in [0..150] | not IsPrime(10*n + 1)]; // _Vincenzo Librandi_, Jan 12 2013
%Y Cf. A024912, A053178, A153329.
%K nonn,easy
%O 1,2
%A _Vincenzo Librandi_, Dec 22 2008
%E 63 replaced by 53 by _R. J. Mathar_, Jan 23 2009
%E 0 added by _Arkadiusz Wesolowski_, Aug 03 2011
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