A046463 Numbers k such that the concatenation of numbers from 1 to k is the product of 4 primes (not necessarily distinct).

9, 16, 23, 29, 37, 38, 43, 58, 59

Offset: 1

Author

Patrick De Geest, Aug 15 1998

Keywords

• nonn
• hard
• base

Links

• Patrick De Geest, Normal Smarandache Concatenated Numbers, Prime factors from 1 up to n
• M. Fleuren, Factors and primes of Smarandache sequences.
• Carlos Rivera, Primes by Listing, The Prime Puzzles & Problems Connection.

Crossrefs

Cf. A046460.

Programs

Mathematica

Select[Range[60],PrimeOmega[FromDigits[Flatten[IntegerDigits/@ Range[#]]]] == 4&] (* Harvey P. Dale, Jan 15 2013 *)