A102821 Numbers n for which the square excess of n-th prime is prime.

2, 4, 5, 8, 9, 13, 14, 15, 19, 20, 23, 27, 28, 30, 35, 36, 37, 38, 39, 46, 49, 56, 57, 67, 68, 69, 71, 81, 83, 86, 93, 94, 96, 98, 107, 108, 109, 111, 112, 113, 114, 124, 128, 138, 139, 142, 144, 155, 156, 157, 158, 159, 160, 161, 162, 173, 178, 182, 192, 195, 196, 199

Offset

0,1

Links

Table of n, a(n) for n=0..61.

Example

7 - 2^2 = 3 is the square excess (see A056892) of 7 and it is prime. 7 is the 4th prime, so 4 is in the sequence.

Mathematica

Select[Range[200], PrimeQ[Prime[#]-Floor[Sqrt[Prime[#]]]^2]&] (* Harvey P. Dale, Jul 06 2014 *)

Crossrefs

Cf. A056892.

Sequence in context: A189134 A189019 A189016 * A101881 A143989 A064573

Adjacent sequences: A102818 A102819 A102820 * A102822 A102823 A102824

Keyword

easy,nonn

Author

Olaf Voß, Feb 27 2005

Status

approved