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A015049 Let m = A013929(n); then a(n) = smallest k such that m divides k^2. 5
2, 4, 3, 6, 4, 6, 10, 12, 5, 9, 14, 8, 6, 20, 22, 15, 12, 7, 10, 26, 18, 28, 30, 21, 8, 34, 12, 15, 38, 20, 9, 42, 44, 30, 46, 24, 14, 33, 10, 52, 18, 28, 58, 39, 60, 11, 62, 25, 42, 16, 66, 45, 68, 70, 12, 21, 74, 30, 76, 51, 78, 40, 18, 82, 84, 13, 57, 86 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
Henry Ibstedt, Surfing on the Ocean of Numbers, Erhus Univ. Press, Vail, 1997.
FORMULA
a(n) = A019554(A013929(n)).
Sum_{k=1..n} a(k) ~ c * n^2 / 2, where c = zeta(2)*(zeta(3)-1)/(zeta(2)-1)^2 = 0.799082... . - Amiram Eldar, Jan 06 2024
MATHEMATICA
f[p_, e_] := p^Ceiling[e/2]; s[1] = 1; s[n_] := Times @@ f @@@ FactorInteger[n]; s /@ Select[Range[200], !SquareFreeQ[#] &] (* Amiram Eldar, Feb 10 2021 *)
PROG
(PARI) lista(kmax) = {my(f); for(k = 2, kmax, f = factor(k); if(!issquarefree(f), print1(k/core(f, 1)[2], ", "))); } \\ Amiram Eldar, Jan 06 2024
CROSSREFS
Sequence in context: A239466 A129509 A341844 * A057956 A151734 A175027
KEYWORD
nonn
AUTHOR
R. Muller
EXTENSIONS
Description corrected by Diego Torres (torresvillarroel(AT)hotmail.com), Jun 23 2002
Offset corrected by Amiram Eldar, Feb 10 2021
STATUS
approved

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Last modified March 18 22:34 EDT 2024. Contains 370951 sequences. (Running on oeis4.)