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Primes of form n^2 + 20736.
14

%I #6 May 02 2017 21:45:34

%S 20857,21577,21961,23761,27961,28657,29017,29761,30937,33961,34897,

%T 37897,41761,42937,49297,51361,60337,62761,65257,80761,83737,93097,

%U 107761,111337,113761,122497,132961,142537,151057,164377,173617,181537,188017,192961,218761

%N Primes of form n^2 + 20736.

%C Conjecture: sequence is infinite.

%H Reinhard Zumkeller, <a href="/A256840/b256840.txt">Table of n, a(n) for n = 1..10000</a>

%H J. Gebel, <a href="/A001014/a001014.txt">Integer points on Mordell curves</a> [Cached copy, after the original web site tnt.math.se.tmu.ac.jp was shut down in 2017]

%o (Haskell)

%o a256840 n = a256840_list !! (n-1)

%o a256840_list = [x | x <- map (+ 20736) a000290_list, a010051' x == 1]

%Y Cf. A010051, A000290; subsequence of A028916.

%Y Primes of form n^2+b^4, b fixed: A002496 (b=1), A243451 (b=2), A256775 (b=3), A256776 (b=4), A256777 (b=5), A256834 (b=6), A256835 (b=7), A256836 (b=8), A256837 (b=9), A256838 (b=10), A256839 (b=11), A256841 (b=13).

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Apr 11 2015