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A128215
a(1)=a(2)=1. a(n+1) = a(n) + a(largest prime dividing n).
2
1, 1, 2, 4, 5, 10, 12, 24, 25, 27, 32, 64, 66, 132, 144, 149, 150, 300, 302, 604, 609, 621, 653, 1306, 1308, 1313, 1379, 1381, 1393, 2786, 2791, 5582, 5583, 5615, 5765, 5777, 5779, 11558, 11860, 11926, 11931, 23862, 23874, 47748, 47780, 47785, 48438, 96876
OFFSET
1,3
LINKS
EXAMPLE
The largest prime dividing 12 is 3. So a(13) = a(12) + a(3) = 64 + 2 = 66.
MAPLE
with(numtheory): a[1]:=1:a[2]:=1:for n from 2 to 55 do a[n+1]:=a[n]+a[factorset(n)[nops(factorset(n))]] od: seq(a[n], n=1..55); # Emeric Deutsch, Mar 07 2007
MATHEMATICA
a128215[1] = 1; a128215[2] = 1;
a128215[n_] := a128215[n] = a128215[n-1] + a128215[First[Last[FactorInteger[n-1]]]];
Array[a128215, 48] (* data *) (* Hartmut F. W. Hoft, Mar 08 2017 *)
CROSSREFS
Sequence in context: A133732 A328221 A364913 * A325676 A097132 A321683
KEYWORD
nonn
AUTHOR
Leroy Quet, Feb 19 2007
EXTENSIONS
More terms from Emeric Deutsch, Mar 07 2007
STATUS
approved