A235812 a(n) is the start of the earliest run of n numbers such that the sum of their digits is equal to the sum of the digits of their prime factors.

2, 2, 2, 2, 1458855, 1790478, 429990136, 4475873320, 1979414080360

Offset: 1

Author

Giovanni Resta, Jan 16 2014

Keywords

• nonn
• base

Comments

This sequence takes into account both primes and Smith numbers (A006753).

a(10) > 5*10^12.

Examples

			The four numbers 2, 3, 4, 5 are either prime (2, 3, 5) or Smith (4) numbers. In any case, the sum of their digits is equal to the sum of their prime factors (counted with multiplicity), hence a(1) = a(2) = a(3) = a(4) = 2.
		

Links

• C. Rivera, Puzzle 247. Consecutive Smith numbers

Crossrefs

Cf. A006753, A059754.