A317399 Positive integers that have exactly nine representations of the form 1 + p1 * (1 + p2* ... * (1 + p_j)...), where [p1, ..., p_j] is a (possibly empty) list of distinct primes.
7021, 7162, 8053, 8737, 9178, 9556, 10126, 10858, 10861, 10866, 11113, 11133, 11363, 11740, 12076, 12111, 12666, 13168, 13210, 13339, 13573, 13729, 14037, 14366, 14411, 14691, 15250, 15478, 15569, 15653, 15726, 15922, 16066, 16113, 16116, 16386, 16459, 16644
Offset: 1
Keywords
Links
- Alois P. Heinz, Table of n, a(n) for n = 1..20000
Programs
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Maple
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<10 do r:= r+b((n-1)/p, s union {p}) od; `if`(r<10, r, 10) fi end: a:= proc(n) option remember; local k; for k from `if`(n=1, 1, 1+a(n-1)) while b(k, {})<>9 do od; k end: seq(a(n), n=1..100);
Formula
A317241(a(n)) = 9.