cp's OEIS Frontend

A340634 Numbers k such that k + A037276(k) is prime.

%I A340634 #13 Feb 06 2021 22:09:37
%S A340634 1,6,14,18,22,26,34,36,38,46,48,62,66,74,106,108,110,122,134,146,156,
%T A340634 166,170,174,178,194,196,198,206,226,230,254,262,274,278,290,294,298,
%U A340634 306,318,354,362,374,386,392,394,416,420,422,426,458,466,468,490,502,504,516,526,528,530,532,544,562
%N A340634 Numbers k such that k + A037276(k) is prime.
%C A340634 All terms except 1 are even.
%H A340634 Robert Israel, <a href="/A340634/b340634.txt">Table of n, a(n) for n = 1..10000</a>
%e A340634 a(3) = 14 is a term because 14 + A037276(14) = 14 + 27 = 41 is prime.
%p A340634 dcat:= proc(L) local i, x;
%p A340634   x:= L[-1];
%p A340634   for i from nops(L)-1 to 1 by -1 do
%p A340634     x:= 10^(1+ilog10(x))*L[i]+x
%p A340634   od;
%p A340634   x
%p A340634 end proc:
%p A340634 A037276:= proc(n) local F;
%p A340634   F:= sort(ifactors(n)[2], (a, b) -> a[1] < b[1]);
%p A340634   dcat(map(t -> t[1]$t[2], F));
%p A340634 end proc:
%p A340634 A037276(1):= 1:
%p A340634 select(t -> isprime(t + A037276(t)), [1,seq(i,i=3..1000)]);
%Y A340634 Cf. A037276, A340633, A340636.
%K A340634 nonn,base
%O A340634 1,2
%A A340634 _J. M. Bergot_ and _Robert Israel_, Jan 14 2021