

A242384


Lesser of consecutive primes whose sum is of the form k*(k+2), for some integer k.


2



3, 11, 59, 139, 179, 311, 419, 541, 919, 1399, 1621, 2111, 3119, 5099, 6379, 8059, 8839, 9377, 15661, 16007, 16741, 17107, 21011, 21839, 23539, 24419, 28081, 30011, 31489, 33533, 35617, 37811, 39461, 41759, 44699, 45293, 60899, 68819, 71059, 78007, 83639, 84457, 86111
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OFFSET

1,1


LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..500


EXAMPLE

311 is in the sequence because 311 is prime, nextprime(311)=313, and 311+313 = 624 = 24*(24+2).


MATHEMATICA

Select[Partition[Prime[Range[9000]], 2, 1], IntegerQ[Sqrt[1+Total[#]]1]&] [[All, 1]] (* Harvey P. Dale, May 15 2017 *)


PROG

(PARI) {k=2; while(k<10^5, l=nextprime(k+1); if(issquare(k+l+1), print1(k, ", ")); k=l)}


CROSSREFS

Cf. A242383, A242385.
Sequence in context: A137690 A107007 A199854 * A225809 A267607 A319248
Adjacent sequences: A242381 A242382 A242383 * A242385 A242386 A242387


KEYWORD

nonn


AUTHOR

Antonio Roldán, May 12 2014


STATUS

approved



