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A317395
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Positive integers that have exactly five representations of the form 1 + p1 * (1 + p2* ... * (1 + p_j)...), where [p1, ..., p_j] is a (possibly empty) list of distinct primes.
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2
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638, 848, 921, 969, 1002, 1026, 1106, 1156, 1191, 1248, 1276, 1310, 1326, 1341, 1431, 1444, 1480, 1499, 1548, 1592, 1641, 1730, 1764, 1772, 1786, 1856, 1888, 1911, 1996, 2005, 2025, 2038, 2050, 2053, 2061, 2121, 2129, 2131, 2133, 2146, 2171, 2224, 2256, 2258
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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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MAPLE
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b:= proc(n, s) option remember; local p, r; if n=1 then 1 else r:=0;
for p in numtheory[factorset](n-1) minus s while r<6
do r:= r+b((n-1)/p, s union {p}) od; `if`(r<6, r, 6)
fi
end:
a:= proc(n) option remember; local k; for k from
`if`(n=1, 1, 1+a(n-1)) while b(k, {})<>5 do od; k
end:
seq(a(n), n=1..100);
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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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