

A234372


Second smallest prime congruent to 1 modulo nth prime.


2



5, 13, 31, 43, 67, 79, 137, 229, 139, 233, 373, 223, 739, 431, 659, 743, 827, 733, 1609, 853, 439, 1423, 499, 1069, 971, 809, 1031, 857, 2399, 1583, 2287, 787, 1097, 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
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OFFSET

1,1


COMMENTS

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


LINKS



EXAMPLE

a(3) = 31 because prime(3) = 5, first prime == 1 (mod 5) is 11 and 2nd one is 31.
a(4) = 43 because prime(4) = 7, first prime == 1 (mod 7) is 29 and 2nd one is 43.


MATHEMATICA

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}]


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



