cp's OEIS Frontend

A036336 Smallest positive integer with n digits and exactly n prime factors (counted with multiplicity).

%I A036336 #24 Feb 22 2021 01:39:48
%S A036336 2,10,102,1012,10010,100040,1000125,10000096,100000032,1000000080,
%T A036336 10000000080,100000000512,1000000001280,10000000014336,
%U A036336 100000000004096,1000000000010880,10000000000008192,100000000000008192,1000000000000010240,10000000000000045056
%N A036336 Smallest positive integer with n digits and exactly n prime factors (counted with multiplicity).
%H A036336 David A. Corneth, <a href="/A036336/b036336.txt">Table of n, a(n) for n = 1..29</a>
%H A036336 Carlos Rivera, <a href="http://www.primepuzzles.net/puzzles/puzz_025.htm">Puzzle 25. Composed primes</a>, The Prime Puzzles and Problems Connection.
%p A036336 f:= proc(n) local k;
%p A036336   for k from 10^(n-1) do
%p A036336     if numtheory:-bigomega(k) = n then return k fi
%p A036336   od
%p A036336 end proc:
%p A036336 map(f, [$1..20]); # _Robert Israel_, May 31 2018
%t A036336 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 *)
%o A036336 (Python)
%o A036336 from sympy import factorint
%o A036336 def a(n):
%o A036336   for m in range(10**(n-1), 10**n):
%o A036336     if sum(factorint(m).values()) == n: return m
%o A036336 print([a(n) for n in range(1, 13)]) # _Michael S. Branicky_, Feb 10 2021
%Y A036336 Cf. A036335, A036337, A036338.
%K A036336 nonn,base
%O A036336 1,1
%A A036336 _Patrick De Geest_, Dec 15 1998
%E A036336 More terms from _Matthew Conroy_, May 27 2001
%E A036336 Offset corrected, and a(19)-a(20) from _Robert Israel_, May 31 2018