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A188348 Distance between n and the next number with the same number of distinct prime factors. 1
1, 1, 1, 2, 4, 1, 1, 2, 2, 2, 2, 3, 1, 3, 1, 2, 2, 4, 1, 1, 2, 2, 2, 2, 2, 2, 5, 2, 12, 1, 5, 1, 1, 1, 2, 4, 1, 1, 4, 2, 18, 4, 1, 1, 2, 2, 2, 4, 1, 1, 2, 6, 1, 1, 1, 1, 4, 2, 6, 3, 1, 2, 3, 3, 4, 4, 1, 3, 8, 2, 2, 6, 1, 1, 1, 3, 6, 2, 2, 2, 3, 6, 6, 1, 1, 1, 3, 8, 12 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,4

LINKS

Robert Israel, Table of n, a(n) for n = 2..10000

FORMULA

{min d>0: A001221(n+d) = A001221(n)}.

MAPLE

N:= 200: # to use numbers up to N

V:= Array(2..N, n -> nops(numtheory:-factorset(n))):

A:= Array(2..N):

for n from 2 to N do

  v:= V[n];

  if assigned(Last[v]) then

     A[Last[v]]:= n-Last[v]

  fi;

  Last[v]:= n;

od:

m:= min(select(t -> A[t]=0, [$2..N]))-1:

seq(A[i], i=2..m); # Robert Israel, Jan 24 2020

PROG

(PARI) for(n=2, 100, f=omega(n); m=n+1; while(omega(m)!=f, m++); print1(m-n, ", ")) \\ Colin Barker, Jun 27 2014

CROSSREFS

Cf. A001221, A178139.

Sequence in context: A094643 A094593 A327814 * A336434 A007738 A186520

Adjacent sequences:  A188345 A188346 A188347 * A188349 A188350 A188351

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Mar 28 2011

EXTENSIONS

Renamed, edited and checked by R. J. Mathar, Mar 28 2011.

STATUS

approved

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Last modified May 10 01:03 EDT 2021. Contains 343747 sequences. (Running on oeis4.)