A247514 Numbers k such that 2*floor(sqrt(prime(k))) = floor(2*sqrt(prime(k))).

1, 3, 5, 7, 8, 10, 12, 13, 16, 19, 20, 23, 24, 26, 27, 28, 29, 31, 32, 35, 36, 40, 41, 42, 45, 46, 49, 50, 51, 52, 55, 56, 57, 58, 62, 67, 68, 73, 74, 75, 79, 80, 81, 86, 87, 88, 89, 93, 94, 95, 96, 100, 101, 106, 107, 108, 109, 115, 116, 117, 118, 123, 124

Offset: 1

Author

Reinhard Zumkeller, Sep 20 2014

Keywords

• nonn

Comments

A117767(a(n)) = A247485(a(n)); complement of A247515.

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A117767, A247485, A000196, A000040, A000006, A247515.

Programs

Haskell

a247514 n = a247514_list !! (n-1)
a247514_list = filter (\x -> a117767 x == a247485 x) [1..]

Mathematica

A247514Q[k_]:=With[{r=Sqrt[Prime[k]]},2Floor[r]==Floor[2r]];
Select[Range[200],A247514Q] (* Paolo Xausa, Oct 23 2023 *)

PARI

isok(k) = my(p=prime(k)); 2*sqrtint(p) == sqrtint(4*p); \\ Michel Marcus, Apr 29 2023