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A082544
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Number of ordered quintuples (a,b,c,d,e) with gcd(a,b,c,d,e)=1 (1<= {a,b,c,d,e} <= n).
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9
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1, 31, 241, 991, 3091, 7501, 16531, 31711, 57781, 96601, 157651, 240031, 362491, 519961, 739201, 1012441, 1383721, 1822711, 2409241, 3091441, 3966301, 4974751, 6257461, 7680781, 9481681, 11474941, 13916191, 16610371, 19911151, 23435191
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OFFSET
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1,2
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LINKS
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FORMULA
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a(n) = Sum_{k=1..n} mu(k)*floor(n/k)^5; a(n) is asymptotic to c*n^5 with c=0.9643....
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PROG
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(PARI) a(n)=sum(k=1, n, moebius(k)*floor(n/k)^5)
(Python)
from functools import lru_cache
@lru_cache(maxsize=None)
if n == 0:
return 0
c, j = 1, 2
k1 = n//j
while k1 > 1:
j2 = n//k1 + 1
j, k1 = j2, n//j2
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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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