A199166 Smallest number with all identical digits having n prime factors with multiplicity.

2, 4, 8, 88, 888, 222222, 444444, 888888, 444444444444, 888888888888, 444444444444444444, 888888888888888888, 888888888888888888888888, 222222222222222222222222222222, 444444444444444444444444444444, 888888888888888888888888888888

Offset: 1

Author

Michel Lagneau, Nov 03 2011

Keywords

• nonn
• base

Examples

			a(7) = 444444 = 2^2*3*7*11*13*37 has 7 prime factors with multiplicity, hence 444444 is in the sequence.
		

Crossrefs

Cf. A087331.

Programs

Maple

with(numtheory):for n from 1 to 17 do:i:=0:for k from 1 to 60 while(i=0)do:for a from 1 to 9 while(i=0)do:x:=((10^k- 1)/9)*a:if bigomega(x)=n then i:=1:printf(`%d, `,x):else fi:od:od:od:

Mathematica

Table[digs = 1; While[i = 1; While[num = FromDigits[Table[i, {digs}]]; stop = (i > 9) || PrimeOmega[num] == n; ! stop, i++]; i > 9, digs++]; num, {n, 16}] (* T. D. Noe, Nov 03 2011 *)

Formula

min{ A010785(k): A001222(A010785(k)) = n}. - R. J. Mathar, Nov 03 2011