A372607 - OEIS

A372607

Let a(1) = 2, f(n) = a(1)*a(2)*...*a(n-1) for n >= 1 and a(n) = nextludicnumber(f(n)+1) - f(n) for n >= 2, where nextludicnumber(x) is the smallest ludic number > x.

%I #21 Nov 06 2024 04:44:09

%S 2,3,5,7,11,23,13,25,17

%N Let a(1) = 2, f(n) = a(1)*a(2)*...*a(n-1) for n >= 1 and a(n) = nextludicnumber(f(n)+1) - f(n) for n >= 2, where nextludicnumber(x) is the smallest ludic number > x.

%C Conjecture: every element is a ludic number.

%C This is the analog of Buss' conjecture (cf. A067836) for ludic numbers instead of primes, and similar to the idea of ludic Fortunate numbers (A376237) in analogy to the usual Fortunate numbers A005235. - _M. F. Hasler_, Nov 04 2024

%o (PARI) A372607_upto(n=15, f=1)=vector(n,i,n=if(i>1, next_A003309(1+f*=n)-f,2)) \\ _M. F. Hasler_, Nov 02 2024

%Y Cf. A067836, A003309 (ludic numbers), A376237 (ludic Fortunate numbers).

%K nonn,more,hard

%O 1,1

%A _Davide Rotondo_, May 07 2024