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A036336 Smallest positive integer with n digits and exactly n prime factors (counted with multiplicity). 7
2, 10, 102, 1012, 10010, 100040, 1000125, 10000096, 100000032, 1000000080, 10000000080, 100000000512, 1000000001280, 10000000014336, 100000000004096, 1000000000010880, 10000000000008192, 100000000000008192, 1000000000000010240, 10000000000000045056 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

David A. Corneth, Table of n, a(n) for n = 1..29

Carlos Rivera, Puzzle 25. Composed primes, The Prime Puzzles and Problems Connection.

MAPLE

f:= proc(n) local k;

  for k from 10^(n-1) do

    if numtheory:-bigomega(k) = n then return k fi

  od

end proc:

map(f, [$1..20]); # Robert Israel, May 31 2018

MATHEMATICA

npf[n_]:=Module[{k=1, st=10^(n-1)-1}, While[PrimeOmega[st+k]!=n, k++]; st+k]; Array[npf, 20] (* Harvey P. Dale, Mar 25 2012 *)

PROG

(Python)

from sympy import factorint

def a(n):

  for m in range(10**(n-1), 10**n):

    if sum(factorint(m).values()) == n: return m

print([a(n) for n in range(1, 13)]) # Michael S. Branicky, Feb 10 2021

CROSSREFS

Cf. A036335, A036337, A036338.

Sequence in context: A228120 A074109 A291101 * A070842 A086927 A342108

Adjacent sequences:  A036333 A036334 A036335 * A036337 A036338 A036339

KEYWORD

nonn,base

AUTHOR

Patrick De Geest, Dec 15 1998

EXTENSIONS

More terms from Matthew Conroy, May 27 2001

Offset corrected, and a(19)-a(20) from Robert Israel, May 31 2018

STATUS

approved

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Last modified April 18 03:59 EDT 2021. Contains 343072 sequences. (Running on oeis4.)