OFFSET
1,1
COMMENTS
A generalization of Ruth-Aaron pairs (A006145).
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Harvey P. Dale)
FORMULA
sopfr(k+1) mod sopfr(k) = 0.
EXAMPLE
a(6)=160 since sopfr(160)=sopfr(2^5*5)=10+5=15 and sopfr(161)=sopfr(7*23)=30.
MATHEMATICA
sopf[n_]:=Total[Flatten[Table[#[[1]], {#[[2]]}]&/@FactorInteger[n]]]; Rest[ Flatten[Position[Partition[Table[sopf[n], {n, 5200}], 2, 1], _?(Divisible[#[[2]], #[[1]]]&), {1}, Heads->False]]] (* Harvey P. Dale, Jul 18 2013 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Walter Kehowski, Apr 09 2007
STATUS
approved