A152445 - OEIS

A152445

a(0) = a(1) = 1. For n >= 2, a(n) = the smallest prime >= a(n-1)*a(n-2).

%I #15 Jun 30 2020 14:50:42

%S 1,1,2,2,5,11,59,653,38543,25168589,970072925867,24415366771173991757,

%T 23684686279828682858246730078719,

%U 578270302382209771209755703072864217352250067119367

%N a(0) = a(1) = 1. For n >= 2, a(n) = the smallest prime >= a(n-1)*a(n-2).

%p A152445 := proc(n) option remember ; if n <= 1 then 1; else nextprime(procname(n-1)*procname(n-2)-1) ; fi; end: for n from 0 to 15 do printf("%d,",A152445(n)) ; od; # _R. J. Mathar_, Dec 05 2008

%t a = {1, 1, 2, 2}; Do[AppendTo[a, Prime[PrimePi[a[[ -1]]*a[[ -2]]] + 1]], {7}]; a (* _Stefan Steinerberger_, Dec 06 2008 *)

%t nxt[{a_,b_}]:={b,NextPrime[a*b-1]}; NestList[nxt,{1,1},15][[All,1]] (* _Harvey P. Dale_, Jun 30 2020 *)

%Y Cf. A090253, A152446.

%K nonn

%O 0,3

%A _Leroy Quet_, Dec 04 2008

%E Extended beyond a(7) by _R. J. Mathar_, _Stefan Steinerberger_ and _Ray Chandler_, Dec 05 2008