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A286258
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Compound filter: a(n) = P(A046523(n), A046523(2n+1)), where P(n,k) is sequence A000027 used as a pairing function.
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6
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2, 5, 5, 25, 5, 27, 23, 44, 14, 61, 5, 117, 38, 27, 27, 226, 23, 90, 23, 90, 27, 142, 5, 375, 40, 27, 86, 148, 5, 495, 80, 698, 27, 61, 27, 702, 80, 61, 27, 765, 5, 625, 23, 90, 148, 61, 23, 1224, 109, 90, 27, 832, 5, 324, 61, 324, 61, 142, 23, 2013, 23, 84, 90, 2410, 27, 625, 302, 90, 27, 625, 23, 2998, 80, 27, 90, 265, 61, 495, 23, 1426, 152, 601, 5, 2013, 142, 27, 142
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OFFSET
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1,1
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LINKS
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FORMULA
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PROG
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(PARI)
A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); }; \\ This function from Charles R Greathouse IV, Aug 17 2011
for(n=1, 10000, write("b286258.txt", n, " ", A286258(n)));
(Python)
from sympy import factorint
def T(n, m): return ((n + m)**2 - n - 3*m + 2)/2
def P(n):
f = factorint(n)
return sorted([f[i] for i in f])
def a046523(n):
x=1
while True:
if P(n) == P(x): return x
else: x+=1
def a(n): return T(a046523(n), a046523(2*n + 1)) # Indranil Ghosh, May 07 2017
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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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