

A224795


Smallest prime q such that 2n+1 = 2p  q^3 for some odd prime p, or 0 if no such prime exists.


2



7, 17, 3, 5, 3, 61, 7, 5, 3, 5, 11, 37, 0, 53, 3, 5, 3, 13, 7, 5, 7, 37, 3, 13, 7, 5, 3, 193, 3, 13, 19, 29, 3, 5, 11, 109, 19, 5, 3, 5, 131, 109, 11, 5, 3, 5, 3, 61, 23, 5, 7, 13, 3, 13, 7, 29, 3, 29, 3, 73, 7, 0, 331, 5, 3, 61, 7, 5, 3, 53, 59, 13, 11, 5, 3
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OFFSET

1,1


COMMENTS

See the conjecture and the comments in A224794, and the corresponding primes p.


LINKS

Michel Lagneau, Table of n, a(n) for n = 1..10000


EXAMPLE

a(4) = 5 because, for (p, q) = (67, 5), 2*4+1 = 9 = 2*67  5^3 = 134  125 = 9.


MAPLE

for n from 3 by 2 to 200 do:jj:=0:for j from 1 to 50000 while (jj=0) do:q:=ithprime(j):p:=(q^3+n)/2:if type(p, prime)=true then jj:=1: printf(`%d, `, q):else fi:od:if jj=0 then printf(`%d, `, 0):else fi:od:


CROSSREFS

Cf. A224730, A185046, A224794.
Sequence in context: A107778 A122735 A094464 * A138449 A156680 A107804
Adjacent sequences: A224792 A224793 A224794 * A224796 A224797 A224798


KEYWORD

nonn


AUTHOR

Michel Lagneau, Apr 18 2013


STATUS

approved



