

A122478


Minimum number k>0 such that ((2n+1)^k  (2n1)^k)/2 is prime.


2



3, 13, 3, 3, 5, 3, 17, 3, 163, 3, 3, 109, 3, 13, 19, 5, 3, 3, 1879, 3, 13, 379, 7, 1531, 7, 5, 337, 5, 3, 61, 19, 3, 23, 3, 11, 16417, 163, 23, 3, 5, 3, 3, 3, 5
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OFFSET

1,1


COMMENTS

All a(n) are primes. Corresponding minimal primes of the form ((2n+1)^k  (2n1)^k)/2 are {13, 609554401, 109, 193, 51001, 433, 44937854708156010721, 769, ...}.
a(46)a(49) are 17, 5, 31, 3. a(51)a(61) are 109, 5, 7, 89, 13, 3, 31, 53, 5, 3, 5. a(63)a(69) are 3, 7, 19, 5, 167, 163, 293. a(71)a(74) are 3, 3407, 3, 3. a(76)a(77) are 3, 19.
a(45), a(50), a(62), a(70), a(75) are currently unknown.
a(45) > 30000. [From Max Alekseyev, May 18 2010]


LINKS

Table of n, a(n) for n=1..44.


CROSSREFS

Cf. A028491, A121877.
Sequence in context: A010258 A107774 A253685 * A164558 A128368 A050089
Adjacent sequences: A122475 A122476 A122477 * A122479 A122480 A122481


KEYWORD

hard,more,nonn


AUTHOR

Alexander Adamchuk, Sep 14 2006, Sep 17 2006, Oct 07 2006


EXTENSIONS

a(36)=16417 from Max Alekseyev, May 11 2010


STATUS

approved



