A093441 - OEIS

A093441

Lexicographically earliest sequence of primes such that a(n) - 1 == 0 (mod a(n - 1) - 1) where a(n) - 1 is a squarefree number; a(1) = 3.

%I #18 Jan 19 2023 09:36:28

%S 3,7,31,211,2311,43891,1272811,16546531,976245271,36121074991,

%T 1119753324691,52628406260431,3526103219448811,186883470630786931,

%U 7662222295862264131,743235562698639620611,54256196077000692304531,6130950156701078230411891,631487866140211057732424671

%N Lexicographically earliest sequence of primes such that a(n) - 1 == 0 (mod a(n - 1) - 1) where a(n) - 1 is a squarefree number; a(1) = 3.

%H Amiram Eldar, <a href="/A093441/b093441.txt">Table of n, a(n) for n = 1..341</a>

%t a[1] = 3; a[n_] := a[n] = Block[{k = m = a[n - 1] - 1}, k *= 2; While[ !PrimeQ[k + 1] || !SquareFreeQ[k], k += m]; k + 1]; Table[ a[n], {n, 17}] (* _Robert G. Wilson v_, Apr 30 2004 *)

%Y Cf. A073918, A093442.

%Y Distinct from A073918.

%Y Cf. A083772. - _R. J. Mathar_, Sep 05 2008

%K nonn

%O 1,1

%A _Amarnath Murthy_, Apr 01 2004

%E a(7)-a(17) from _Robert G. Wilson v_, Apr 30 2004

%E a(18)-a(19) from _Amiram Eldar_, Jan 19 2023