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A305809 Dirichlet convolution of A003415 (Arithmetic derivative) with itself. 11
0, 0, 0, 1, 0, 2, 0, 8, 1, 2, 0, 18, 0, 2, 2, 40, 0, 22, 0, 22, 2, 2, 0, 96, 1, 2, 12, 26, 0, 40, 0, 160, 2, 2, 2, 147, 0, 2, 2, 128, 0, 48, 0, 34, 28, 2, 0, 400, 1, 34, 2, 38, 0, 156, 2, 160, 2, 2, 0, 276, 0, 2, 32, 560, 2, 64, 0, 46, 2, 56, 0, 680, 0, 2, 36, 50, 2, 72, 0, 560, 90, 2, 0, 348, 2, 2, 2, 224, 0, 346, 2, 58, 2, 2, 2, 1440, 0, 46, 40, 267, 0, 88 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,6
LINKS
FORMULA
a(n) = Sum_{d|n} A003415(n/d)*A003415(d).
PROG
(PARI)
A003415(n) = {my(fac); if(n<1, 0, fac=factor(n); sum(i=1, matsize(fac)[1], n*fac[i, 2]/fac[i, 1]))}; \\ From A003415
A305809(n) = sumdiv(n, d, A003415(n/d)*A003415(d));
CROSSREFS
Cf. A008578 (positions of 0's), A001248 (of 1's), A006881 (of 2's).
Sequence in context: A239275 A186745 A109573 * A349139 A159810 A199268
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jun 13 2018
STATUS
approved

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)