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A234372 Second smallest prime congruent to 1 modulo n-th prime. 2

%I #11 Oct 08 2022 00:01:50

%S 5,13,31,43,67,79,137,229,139,233,373,223,739,431,659,743,827,733,

%T 1609,853,439,1423,499,1069,971,809,1031,857,2399,1583,2287,787,1097,

%U 1669,1789,1511,3769,2609,5011,1039,1433,1811,2293,1931,4729,2389,4643,6691,5903,5039,1399,1913,2411,4519,9767,5261,3229,2711

%N Second smallest prime congruent to 1 modulo n-th prime.

%C a(10^k) for k=1..10: 233, 11903, 142543, 837833, 36391853, 247773809, 3947342807, 146741381497, 684052904671, 16638454841119.

%H Zak Seidov, <a href="/A234372/b234372.txt">Table of n, a(n) for n = 1..1000</a>

%e a(3) = 31 because prime(3) = 5, first prime == 1 (mod 5) is 11 and 2nd one is 31.

%e a(4) = 43 because prime(4) = 7, first prime == 1 (mod 7) is 29 and 2nd one is 43.

%t Table[If[n<2,5,p=Prime[n];r=1+2*p;While[!PrimeQ[r],r+=2*p];r+=2*p;While[!PrimeQ[r],r+=2*p];r], {n,100}]

%Y Cf. A035095.

%K nonn

%O 1,1

%A _Zak Seidov_, Dec 25 2013

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Last modified February 27 16:21 EST 2024. Contains 370378 sequences. (Running on oeis4.)