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A100573 Smallest difference between distinct prime divisors of n, or 0 if n is a prime power. 2
0, 0, 0, 0, 0, 1, 0, 0, 0, 3, 0, 1, 0, 5, 2, 0, 0, 1, 0, 3, 4, 9, 0, 1, 0, 11, 0, 5, 0, 1, 0, 0, 8, 15, 2, 1, 0, 17, 10, 3, 0, 1, 0, 9, 2, 21, 0, 1, 0, 3, 14, 11, 0, 1, 6, 5, 16, 27, 0, 1, 0, 29, 4, 0, 8, 1, 0, 15, 20, 2, 0, 1, 0, 35, 2, 17, 4, 1, 0, 3, 0, 39, 0, 1, 12, 41, 26, 9, 0, 1, 6, 21, 28, 45 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,10

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..65537

EXAMPLE

For 30 = 2*3*5, 2 and 3 are separated by only 1, so a(30) = 1.

MATHEMATICA

<<NumberTheory`NumberTheoryFunctions` pfl[x_] :=PrimeFactorList[x] pd[x_] :=Delete[RotateLeft[pfl[x]]-pfl[x], -1] Table[Min[pd[w]], {w, 1, 1000}] (* Labos *)

Table[Min[Differences[Transpose[FactorInteger[n]][[1]]]], {n, 100}]/.\[Infinity]->0 (* Harvey P. Dale, Jul 27 2015 *)

PROG

(PARI) A100573(n) = if(omega(n)<=1, 0, my(ps=factor(n)[, 1]); vecmin(vector((#ps)-1, i, ps[i+1]-ps[i]))); \\ Antti Karttunen, Mar 03 2018

CROSSREFS

Cf. also A046665, A297173.

Sequence in context: A100257 A318315 A300228 * A049087 A178921 A046665

Adjacent sequences:  A100570 A100571 A100572 * A100574 A100575 A100576

KEYWORD

nonn

AUTHOR

Leroy Quet, Jan 02 2005

EXTENSIONS

More terms from Labos Elemer, Jan 05 2005

STATUS

approved

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Last modified March 22 17:25 EDT 2019. Contains 321422 sequences. (Running on oeis4.)