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A357587
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If k > 1 and k divides DedekindPsi(k) then A358015(k)/2 is a term of this sequence.
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0
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1, 4, 3, 8, 12, 16, 9, 24, 32, 36, 48, 27, 64, 72, 96, 108, 128, 144, 81, 192, 216, 256, 288, 324, 384, 432, 243, 512, 576, 648, 768, 864, 972, 1024, 1152, 1296, 729, 1536, 1728, 1944, 2048, 2304, 2592, 2916, 3072, 3456, 3888, 4096, 2187, 4608, 5184, 5832, 6144
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OFFSET
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1,2
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COMMENTS
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Equivalently, if k is in A033845 then A358015(k)/2 is in this sequence.
A term of this sequence is a 3-smooth number (A003586).
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LINKS
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MAPLE
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A357587List := proc(sup) local S, A, k, j;
S := select(n -> irem(DedekindPsi(n), n) = 0, [$2..sup]):
A := proc(n) k := padic[ordp](n, 2); j := ifelse(irem(n, 4) = 0, k, 0);
return 2^(j-2)*DedekindPsi(n*2^(-k)) end;
seq(A(k), k = S) end: A357587List(20000);
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MATHEMATICA
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DedekindPsi[n_] := n*Times @@ (1 + 1/FactorInteger[n][[All, 1]]);
A358015[n_] := Module[{k, j}, k = IntegerExponent[n, 2]; j = If[Divisible[n, 4], k, 0]; DedekindPsi[n*2^(-k)]*2^(j - 1)];
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PROG
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(SageMath)
from sage.arith.misc import dedekind_psi
def A357587List(sup):
S = [n for n in srange(2, sup) if n.divides(dedekind_psi(n))]
def A(n):
k = valuation(n, 2)
j = k if Integer(4).divides(n) else 0
return 2^(j-2)*dedekind_psi(n*2^(-k))
return [A(k) for k in S]
print(A357587List(20000))
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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