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323, 899, 1763, 5249, 3239, 979801, 5459, 10763, 9179, 9701, 10403, 12319, 5646547, 24569, 19109, 19043, 22499, 50819, 41309, 32639, 46979, 34579, 39059, 125969, 49769, 49949, 154559, 48554797, 114953, 52532203, 56624063, 195499, 75077, 79799, 72899
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OFFSET
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1,1
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COMMENTS
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By definition (m+1)*phi(a(n)) = m*sigma(a(n)) where m=A065824(n+1).
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LINKS
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EXAMPLE
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PROG
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(Python)
from math import prod
from itertools import count
from sympy import factorint, primepi
m, k = n, primepi(n+1) + n + (n+1>>1)
while m != k:
m, k = k, primepi(k) + n + (k>>1)
m = m-1>>1
for k in count(1):
f = factorint(k)
if (m+1)*k*prod((p-1)**2 for p in f)==m*prod(p**(e+2)-p for p, e in f.items()):
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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