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 A340160 a(n) is the least prime p such that there are exactly n primes of the form p+d where d is a divisor of p-1 or of p+1. 2
 283, 43, 2, 11, 31, 71, 167, 179, 601, 359, 419, 1439, 1559, 3359, 7559, 6047, 5039, 13679, 21001, 13441, 20161, 45361, 15121, 10079, 54001, 41579, 35281, 92399, 99793, 92401, 100801, 65521, 100799, 196561, 241919, 377999, 110879, 451439, 453601, 478801, 498961, 383041, 393121, 262079, 453599 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS Robert Israel, Table of n, a(n) for n = 0..149 EXAMPLE a(3) = 11, with 3 primes of the form 11+t where t is a divisor of 10 or 12, namely 13 = 11+2, 17 = 11+6 and 23=11+12. MAPLE f:= proc(p) nops(select(t -> isprime(t+p), numtheory:-divisors(p-1) union numtheory:-divisors(p+1))) end proc: V:= Array(0..50): count:= 0: p:= 1: while count < 51 do p:= nextprime(p); v:= f(p); if v <= 50 and V[v]=0 then count:= count+1; V[v]:= p; fi od: convert(V, list); CROSSREFS Sequence in context: A172627 A172725 A172804 * A334106 A175276 A334096 Adjacent sequences: A340157 A340158 A340159 * A340161 A340162 A340163 KEYWORD nonn AUTHOR J. M. Bergot and Robert Israel, Dec 29 2020 STATUS approved

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Last modified August 13 05:34 EDT 2024. Contains 375113 sequences. (Running on oeis4.)