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A271676 Prime powers k such that 3k + 4 is a perfect square. 1
4, 7, 32, 64 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

This sequence is complete. For proof see the link. - Altug Alkan, Apr 15 2016

LINKS

Table of n, a(n) for n=1..4.

Altug Alkan, Proof of Fini and Full

EXAMPLE

4 is in this sequence because 3*4 + 4 = 16 = 4^2,

7 is in this sequence because 3*7 + 4 = 25 = 5^2,

32 is in this sequence because 3*32 + 4 = 100 = 10^2,

64 is in this sequence because 3*64 + 4 = 196 = 14^2.

MATHEMATICA

Select[Range[10^4], PrimePowerQ@ # && IntegerQ@ Sqrt[3 # + 4] &] (* Michael De Vlieger, Apr 12 2016 *)

PROG

(MAGMA) [n: n in [2..10000000] | IsPrimePower(n) and IsSquare(3*n + 4)];

(PARI) lista(nn) = for(n=1, nn, if(isprimepower(n) && issquare(3*n+4), print1(n, ", "))); \\ Altug Alkan, Apr 12 2016

CROSSREFS

Cf. A000961, A271675.

Sequence in context: A283332 A000289 A241426 * A149089 A004031 A243863

Adjacent sequences:  A271673 A271674 A271675 * A271677 A271678 A271679

KEYWORD

nonn,fini,full

AUTHOR

Juri-Stepan Gerasimov, Apr 12 2016

STATUS

approved

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Last modified February 23 18:54 EST 2018. Contains 299586 sequences. (Running on oeis4.)