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All distinct primes dividing n are consecutive.
7

%I #26 Jul 07 2015 08:07:18

%S 2,3,4,5,6,7,8,9,11,12,13,15,16,17,18,19,23,24,25,27,29,30,31,32,35,

%T 36,37,41,43,45,47,48,49,53,54,59,60,61,64,67,71,72,73,75,77,79,81,83,

%U 89,90,96,97,101,103,105,107,108,109,113,120,121,125,127,128,131,135,137

%N All distinct primes dividing n are consecutive.

%C If n is a term, any power of n is also a term. Also all primes are terms. - _Zak Seidov_, Jun 25 2015

%H Harry J. Smith and Robert Israel, <a href="/A066311/b066311.txt">Table of n, a(n) for n = 1..10000</a> (1..1000 from Harry J. Smith)

%e 35 is included because 35 = 5 * 7 and 5 and 7 are consecutive primes.

%p select((numtheory:-pi @ max - numtheory:-pi @ min - nops) @ numtheory:-factorset = -1, [$2..1000]); # _Robert Israel_, Jun 25 2015

%t fi[n_]:=FactorInteger[n];Select[Range[2,5903],PrimeQ[#]||Length[fi[#]] < 2 ||Union[Differences[PrimePi[#[[1]]&/@fi[#]]]]=={1}&]

%t (* For first 1000 terms. - _Zak Seidov_, Jun 25 2015 *)

%o (PARI) { n=0; for (m=2, 10^9, f=factor(m); b=1; for (i=2, matsize(f)[1], if (primepi(f[i, 1]) - primepi(f[i - 1, 1]) > 1, b=0; break)); if (b, write("b066311.txt", n++, " ", m); if (n==1000, return)) ) } \\ _Harry J. Smith_, Feb 10 2010

%Y Cf. A066312 (a subsequence).

%K nonn

%O 1,1

%A _Leroy Quet_, Jan 01 2002

%E Offset changed from 0 to 1 by _Harry J. Smith_, Feb 10 2010