A117093 Numbers k such that nextprime(3*k)>3*nextprime(k) (if p is prime then nextprime(p)=p).

2, 3, 5, 7, 11, 13, 16, 17, 18, 19, 23, 28, 29, 30, 31, 37, 38, 39, 40, 41, 43, 47, 53, 58, 59, 61, 67, 71, 72, 73, 78, 79, 81, 82, 83, 88, 89, 95, 96, 97, 98, 99, 100, 101, 103, 106, 107, 108, 109, 113, 127, 130, 131, 137, 138, 139, 148, 149, 150, 151, 156, 157

Offset

1,1

Links

Table of n, a(n) for n=1..62.

Example

nextprime(3*13)=41 and 3*nextprime(13)=3*13=39 then 13 is member because 41>39.

Mathematica

fp[k_]:=If[PrimeQ[k], k, NextPrime[k]]; Select[Range[160], fp[3#]>3fp[#]&] (* James C. McMahon, Aug 23 2024 *)

Prog

(PARI) for(i=1, 100, if(nextprime(3*i)>nextprime(3)*nextprime(i), print1(i, ", ")))

Crossrefs

Cf. A007918 (nextprime).

Sequence in context: A240960 A190223 A086070 * A062063 A211338 A167175

Adjacent sequences: A117090 A117091 A117092 * A117094 A117095 A117096

Keyword

easy,nonn

Author

Mohammed Bouayoun (mohammed.bouayoun(AT)sanef.com), Apr 18 2006

Extensions

a(44)-a(59) from James C. McMahon, Aug 23 2024

Status

approved