A164625 Primes p such that p+floor(p/2)+floor(p/3)+floor(p/5) is also prime.

2, 3, 7, 19, 83, 89, 127, 137, 139, 181, 251, 257, 311, 317, 373, 379, 449, 491, 499, 503, 509, 673, 733, 797, 853, 857, 863, 919, 971, 983, 1033, 1039, 1049, 1093, 1151, 1201, 1217, 1399, 1453, 1579, 1583, 1627, 1697, 1741, 1871, 1933, 1993, 2129, 2237, 2281

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, Aug 17 2009

Keywords

• nonn
• easy

Examples

			For p=7, 7+3+2+1=13 is prime, which admits 7=a(4) to the sequence.
For p=19, 19+9+6+3=37 is prime, which puts 19=a(5) into the sequence.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A038874, A049545, A097933, A164624

Programs

Mathematica

lst={};Do[p=Prime[n];If[PrimeQ[p+Floor[p/2]+Floor[p/3]+Floor[p/5]],AppendTo[lst, p]],{n,2*6!}];lst
Select[Prime[Range[350]],PrimeQ[Total[Floor[#/{2,3,5}]]+#]&] (* Harvey P. Dale, Feb 19 2012 *)

Extensions

Comments rephrased as examples by R. J. Mathar, Aug 20 2009