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 A196127 Union of p-1, 2p-1 and 3p-1 where p is a prime (without repetition). 2
 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 (list; graph; refs; listen; history; text; internal format)
 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

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Last modified December 1 08:49 EST 2023. Contains 367468 sequences. (Running on oeis4.)