Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #5 Jan 17 2014 04:30:13
%S 2,2,2,2,1458855,1790478,429990136,4475873320,1979414080360
%N 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.
%C This sequence takes into account both primes and Smith numbers (A006753).
%C a(10) > 5*10^12.
%H C. Rivera, <a href="http://www.primepuzzles.net/puzzles/puzz_247.htm"> Puzzle 247. Consecutive Smith numbers</a>
%e 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.
%Y Cf. A006753, A059754.
%K nonn,base
%O 1,1
%A _Giovanni Resta_, Jan 16 2014