A239634 Initial digits of semiprimes in decimal representation.

4, 6, 9, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 5, 5, 5, 5, 6, 6, 6, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2

Offset: 1

Author

Reinhard Zumkeller, Mar 23 2014

Keywords

• nonn
• base

Comments

a(n) = A000030(A001358(n)).

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A239639 (run lengths), A106146 (last digits).

Programs

Haskell

a239634 = a000030 . a001358

Mathematica

First[IntegerDigits[#]]&/@Select[Range[300],PrimeOmega[#]==2&] (* Harvey P. Dale, Jul 24 2017 *)