A175760 Numbers n such that d(n + d(n)) = d(n), where d(n) is the sum of the distinct primes dividing n.

1, 2, 39, 95, 119, 182, 2130, 2183, 2356, 2623, 3059, 3431, 3825, 6680, 9588, 10170, 10679, 11790, 14039, 14111, 15030, 16199, 16762, 16799, 17766, 19669, 22218, 24505, 26352, 26353, 34443, 34765, 34875, 36594, 37843, 39121, 39479, 39697, 42210, 44051, 45346

Offset

1,2

Comments

The sum of the distinct primes dividing n (A008472) sometimes called sopf(n).

d(1) = 0 because 1 has no prime divisors. So 1 is in this sequence because d(1+0) = d(1). - T. D. Noe, Jul 06 2012

Links

T. D. Noe, Table of n, a(n) for n = 1..1000

Example

39 is in the sequence because sopf(39) = 16 and sopf(39 + sopf(39)) = sopf(55 ) = 16.

Mathematica

d[n_] := Plus @@ Transpose[FactorInteger[n]][[1]]; Join[{1}, Select[Range[2, 50000], d[# + d[#]] == d[#] &]]

Crossrefs

Sequence in context: A078733 A201360 A227904 * A080920 A086338 A329552

Adjacent sequences: A175757 A175758 A175759 * A175761 A175762 A175763

Keyword

nonn

Author

Michel Lagneau, Aug 28 2010

Status

approved