cp's OEIS Frontend

A317395 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.

%I A317395 #4 Jul 27 2018 10:47:46
%S A317395 638,848,921,969,1002,1026,1106,1156,1191,1248,1276,1310,1326,1341,
%T A317395 1431,1444,1480,1499,1548,1592,1641,1730,1764,1772,1786,1856,1888,
%U A317395 1911,1996,2005,2025,2038,2050,2053,2061,2121,2129,2131,2133,2146,2171,2224,2256,2258
%N A317395 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.
%H A317395 Alois P. Heinz, <a href="/A317395/b317395.txt">Table of n, a(n) for n = 1..20000</a>
%F A317395 A317241(a(n)) = 5.
%p A317395 b:= proc(n, s) option remember; local p, r; if n=1 then 1 else r:=0;
%p A317395       for p in numtheory[factorset](n-1) minus s while r<6
%p A317395         do r:= r+b((n-1)/p, s union {p}) od; `if`(r<6, r, 6)
%p A317395       fi
%p A317395     end:
%p A317395 a:= proc(n) option remember; local k; for k from
%p A317395      `if`(n=1, 1, 1+a(n-1)) while b(k, {})<>5 do od; k
%p A317395     end:
%p A317395 seq(a(n), n=1..100);
%Y A317395 Column k=5 of A317390.
%Y A317395 Cf. A317241.
%K A317395 nonn
%O A317395 1,1
%A A317395 _Alois P. Heinz_, Jul 27 2018