A320021 Numbers equal to the sum of the aliquot parts of the previous k numbers, for some k.
5, 6, 7, 8, 35, 40, 51, 237, 263, 264, 280, 387, 899, 1300, 7300, 8363, 8364, 11764, 26740, 26939, 46595, 59004, 80877, 131580, 5244549, 5462385, 17062317, 75097524, 127838820, 323987589, 1162300835, 1381439877, 4943600220
Offset: 1
Examples
5 is in the sequence because aliquot parts of 4 are 1, 2, of 3 is 1, of 2 is 1: 1 + 2 + 1 + 1 = 5. 6 is in the sequence because aliquot parts of 5 is 1, of 4 are 1, 2, of 3 is 1, of 2 is 1: 1 + 1 + 2 + 1 + 1 = 6. 7 is in the sequence because aliquot parts of 6 are 1, 2, 3, of 5 is 1: 1 + 2 + 3 + 1 = 7.
Programs
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Maple
with(numtheory): P:=proc(q) local a,j,k,n; for n from 1 to q do a:=0; k:=0; while a
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Mathematica
ok[n_] := Block[{s=0, k=n}, While[k>0 && s
Formula
a(n) = Sum_{i = 1..k} A001065(a(n)-i), for some k.
Extensions
a(25)-a(33) from Giovanni Resta, Oct 09 2018
Comments