A113758 a(n) is the least number having sum of digits n in base 10 and also exactly n prime factors (counted with multiplicity).

10001, 12, 40, 32, 240, 3040, 2240, 1152, 6400, 12800, 21504, 440320, 2140160, 172032, 4710400, 1802240, 1327104, 20316160, 40632320, 17301504, 152043520, 602931200, 138412032, 117440512, 3607101440, 1132462080, 51204063232, 3355443200, 35232153600, 202400333824, 102005473280

Offset: 2

Author

Giovanni Resta, Jan 18 2006

Keywords

• base
• nonn

Examples

			a(2)=10001 since 1+0+0+0+1=2 and 10001=73*137 has 2 prime factors.
a(3)=12 since 1+2=3 and 12=2*2*3 has 3 prime factors.
		

Crossrefs

Cf. A115156.

Programs

Mathematica

Lk[n_] := Block[{k = 2}, While[n != Plus @@ IntegerDigits[k] || n != Plus @@ (Transpose[FactorInteger@k][[2]]), k++ ]; k]; L = {}; Do[v = Lk[n]; Print[{n, v}]; AppendTo[L, v], {n, 2, 13}]; L

Extensions

a(23)-a(28) from Donovan Johnson, Nov 15 2009

a(29)-a(32) from Giovanni Resta, Mar 21 2017