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A237201 Smallest integer m such that the n consecutive numbers m, m+1, ..., m+n-1 have n prime factors each, counted with multiplicity; a(n) = 0 if no such number exists. 0
2, 9, 170, 4023, 632148, 4843161124, 1981162639374 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..7.

MATHEMATICA

Table[First@Select[Range[10^6], Union[PrimeOmega[(#+Range[n]-1)]]==={n}&, 1], {n, 5}] Wouter Meeussen, Feb 09 2014

PROG

(Python)

import sympy

from sympy import isprime

from sympy import factorint

def PrimeFact(x):

..n = 9930000

..lst = []

..while n < 10**10:

....if not isprime(n):

......count = 0

......for i in range(n, n+x):

........if sum(factorint(i).values()) == x:

..........count += 1

........else:

..........n += 1

..........break

......if count == x:

........return n

....else:

......n += 1

CROSSREFS

Cf. A001222.

Sequence in context: A182948 A081459 A038843 * A053294 A199695 A078524

Adjacent sequences:  A237198 A237199 A237200 * A237202 A237203 A237204

KEYWORD

nonn,more,hard

AUTHOR

Derek Orr, Feb 04 2014

EXTENSIONS

a(6) from Giovanni Resta, Feb 09 2014

a(7) from Giovanni Resta, Feb 10 2014

STATUS

approved

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Last modified February 27 01:52 EST 2020. Contains 332299 sequences. (Running on oeis4.)