login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A317396 Positive integers that have exactly six representations of the form 1 + p1 * (1 + p2* ... * (1 + p_j)...), where [p1, ..., p_j] is a (possibly empty) list of distinct primes. 2

%I #4 Jul 27 2018 11:01:22

%S 664,1956,2058,2092,2094,2283,2381,2388,2432,2466,2533,2624,2701,2775,

%T 2822,2853,2976,3070,3193,3220,3316,3326,3436,3442,3461,3485,3529,

%U 3568,3571,3576,3620,3746,3784,3785,3797,3826,3839,3913,4005,4026,4031,4213,4234

%N Positive integers that have exactly six representations of the form 1 + p1 * (1 + p2* ... * (1 + p_j)...), where [p1, ..., p_j] is a (possibly empty) list of distinct primes.

%H Alois P. Heinz, <a href="/A317396/b317396.txt">Table of n, a(n) for n = 1..20000</a>

%F A317241(a(n)) = 6.

%p b:= proc(n, s) option remember; local p, r; if n=1 then 1 else r:=0;

%p for p in numtheory[factorset](n-1) minus s while r<7

%p do r:= r+b((n-1)/p, s union {p}) od; `if`(r<7, r, 7)

%p fi

%p end:

%p a:= proc(n) option remember; local k; for k from

%p `if`(n=1, 1, 1+a(n-1)) while b(k, {})<>6 do od; k

%p end:

%p seq(a(n), n=1..100);

%Y Column k=6 of A317390.

%Y Cf. A317241.

%K nonn

%O 1,1

%A _Alois P. Heinz_, Jul 27 2018

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 14 07:07 EDT 2024. Contains 375146 sequences. (Running on oeis4.)