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A272601 Composite n such that p-1 does not divide n-1 for at least one prime divisor of n-1. 2
4, 6, 8, 10, 12, 14, 15, 16, 18, 20, 22, 24, 26, 27, 28, 30, 32, 34, 35, 36, 38, 39, 40, 42, 44, 45, 46, 48, 50, 51, 52, 54, 56, 57, 58, 60, 62, 63, 64, 66, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 82, 84, 86, 87, 88, 90, 91, 92, 93, 94, 95, 96, 98, 99, 100, 102, 104, 105, 106, 108, 110, 111, 112, 114, 115, 116 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Composites not in A272600.

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

MAPLE

with(numtheory): P:=proc(n) local a, k, ok;

if not isprime(n+1) then a:=factorset(n); ok:=0;

for k from 1 to nops(a) do if frac(n/(a[k]-1))>0 then ok:=1;

break; fi; od; if ok=1 then n+1; fi; fi; end: seq(P(i), i=1..115);

# Paolo P. Lava, May 18 2018

PROG

(PARI) forcomposite(n=4, 10^3, my(q=1, f=factor(n-1)[, 1]); for(j=1, #f, if((n-1)%(f[j]-1), q=0; break)); if(!q, print1(n, ", ")));

CROSSREFS

Sequence in context: A134331 A276040 A090334 * A322368 A078941 A078942

Adjacent sequences:  A272598 A272599 A272600 * A272602 A272603 A272604

KEYWORD

nonn

AUTHOR

Joerg Arndt, May 16 2016

STATUS

approved

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Last modified May 21 22:24 EDT 2019. Contains 323467 sequences. (Running on oeis4.)