cp's OEIS Frontend

A089776 If n mod 10 is 1, 3, 7, or 9, then a(n) = least prime of the form 1 followed by n^r; else a(n) = least prime of the form n^r followed by a 1. In both cases r must be > 1 and a(n) = 0 if no such prime exists.

%I A089776 #6 Dec 05 2013 19:56:36
%S A089776 11,41,13,41,251,61,17,641,19,101,114641,0,113,75295361,151,40961,
%T A089776 1289,181,1361,4001,
%U A089776 11025506433613486607375777617584133309366191904729927960524981845743709132117581,1368800680154120519681,1907846434775996175406740561329,241,251,6761,127,281,1500246412961,9001,131
%N A089776 If n mod 10 is 1, 3, 7, or 9, then a(n) = least prime of the form 1 followed by n^r; else a(n) = least prime of the form n^r followed by a 1. In both cases r must be > 1 and a(n) = 0 if no such prime exists.
%C A089776 Subsidiary sequence: 3 more sequences can be obtained by replacing 1 by 3,7 and 9.
%F A089776 If n is divisible by 2 or 5, a(n) = A088622(n); otherwise a(n) = A088623(n). - _David Wasserman_, Oct 12 2005
%e A089776 a(12) = 0 because 1+10*12^r is always divisible by 11.
%e A089776 a(32) = 0 because 1+10*32^r is divisible by 3 if r is odd and by 11 if r is even.
%Y A089776 Cf. A088622, A088623.
%K A089776 base,nonn
%O A089776 1,1
%A A089776 _Amarnath Murthy_, Nov 24 2003
%E A089776 More terms from _David Wasserman_, Oct 12 2005