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A023149 Numbers k such that prime(k) == 7 (mod k).

%I A023149 #27 Feb 11 2021 22:54:13
%S A023149 1,2,4,6,18,36,78,191,6456,6457,40080,40081,637324,637326,637344,
%T A023149 10553425,10553434,10553477,10553502,10553573,10553854,27066988,
%U A023149 27067126,69709680,69709736,69709940,465769818,3140421716,3140421740,3140421743
%N A023149 Numbers k such that prime(k) == 7 (mod k).
%H A023149 Giovanni Resta, <a href="/A023149/b023149.txt">Table of n, a(n) for n = 1..71</a>
%t A023149 p = 1; Do[ If[ Mod[p = NextPrime[p], n] == 7, Print[n]], {n, 1, 10^9}] (* _Robert G. Wilson v_, Feb 18 2004 *)
%o A023149 (Sage)
%o A023149 def A023149(max) :
%o A023149     terms = []
%o A023149     p = 2
%o A023149     for n in range(1, max+1) :
%o A023149         if (p - 7) % n == 0 : terms.append(n)
%o A023149         p = next_prime(p)
%o A023149     return terms
%o A023149 # _Eric M. Schmidt_, Feb 05 2013
%Y A023149 Cf. A171434, A092049, A023143, A023144, A023145, A023146, A023147, A023148, A023150, A023151, A023152.
%K A023149 nonn
%O A023149 1,2
%A A023149 _David W. Wilson_
%E A023149 More terms from _Robert G. Wilson v_, Feb 18 2004
%E A023149 a(27)-a(31) from _Robert G. Wilson v_, Feb 22 2006
%E A023149 First four terms inserted by _Eric M. Schmidt_, Feb 05 2013