A196127 Union of p-1, 2p-1 and 3p-1 where p is a prime (without repetition).

1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 13, 14, 16, 18, 20, 21, 22, 25, 28, 30, 32, 33, 36, 37, 38, 40, 42, 45, 46, 50, 52, 56, 57, 58, 60, 61, 66, 68, 70, 72, 73, 78, 81, 82, 85, 86, 88, 92, 93, 96, 100, 102, 105, 106, 108, 110, 112, 117, 121, 122, 126, 128, 130

Offset

1,2

Links

Nathaniel Johnston, Table of n, a(n) for n = 1..10000

Maple

lim:=70: S:={}: p:=1: for n from 1 to lim do p:=nextprime(p): S := S union {p-1, 2*p-1, 3*p-1}: od: op(1..lim, S); # Nathaniel Johnston, Sep 28 2011

Mathematica

With[{upto=130}, Select[{#-1, 2#-1, 3#-1}&/@Prime[Range[PrimePi[upto]+1]]//Flatten//Union, #<=upto&]] (* Harvey P. Dale, Apr 22 2016 *) (* or *)
Select[Range@130, Or @@ PrimeQ[(#+1)/{1, 2, 3}] &] (* Giovanni Resta, Apr 30 2019 *)

Crossrefs

Cf. A006093, A076274.

Sequence in context: A328216 A071959 A176845 * A194467 A225857 A168134

Adjacent sequences: A196124 A196125 A196126 * A196128 A196129 A196130

Keyword

nonn,easy

Author

Juri-Stepan Gerasimov, Sep 28 2011

Extensions

Entries checked by R. J. Mathar, Sep 28 2011

Status

approved