A117097 - OEIS

A117097

Numbers n such that nextprime(3*n)<3*nextprime(n) (if p is prime then nextprime(p)=p).

1, 4, 6, 8, 9, 10, 12, 14, 15, 20, 21, 22, 24, 25, 26, 27, 32, 33, 34, 35, 36, 42, 44, 45, 46, 48, 49, 50, 51, 52, 54, 55, 56, 57, 60, 62, 63, 64, 65, 66, 68, 69, 70, 74, 75, 76, 77, 80, 84, 85, 86, 87, 90, 91, 92, 93, 94, 102, 104, 105, 110, 111, 112, 114, 115, 116, 117, 118

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Iain Fox, Table of n, a(n) for n = 1..10000

EXAMPLE

nextprime(3*4)=13 and nextprime(3)*nextprime(4)=3*5=15 then 4 is member because 13<15

MATHEMATICA

np[n_]:=If[PrimeQ[n], n, NextPrime[n]]; Select[Range[150], np[3*#]<(3np[#])&] (* Harvey P. Dale, Sep 21 2024 *)

PROG

(PARI) for(i=1, 150, if(nextprime(3*i)<nextprime(3)*nextprime(i), print1(i, ", ")))

CROSSREFS