|
%I #13 Dec 07 2019 12:18:24
%S 1,2,4,8,16,12,4,8,16,12,4,8,16,12,4,8,16,12,4,8,16,12,4,8,16,12,4,8,
%T 16,12,4,8,16,12,4,8,16,12,4,8,16,12,4,8,16,12,4,8,16,12,4,8,16,12,4,
%U 8,16,12,4,8,16,12,4,8,16,12,4,8,16,12,4,8,16,12,4,8,16,12,4,8,16,12,4,8,16
%N Each number is twice times the product of the digits of the previous number.
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (1, -1, 1).
%F From _R. J. Mathar_, Apr 13 2010:
%F a(n) = 2^(n-1) mod 20;
%F a(n) = a(n-1) - a(n-2) + a(n-3), n > 5.
%F G.f.: x*(3*x^2+5*x^3+10*x^4+x+1)/((1-x)*(1+x^2)).
%o (Sage) [power_mod(2,n,20)for n in range(0,85)] # _Zerinvary Lajos_, Nov 03 2009
%K base,nonn
%O 1,2
%A Herman Jamke (hermanjamke(AT)fastmail.fm), Jul 13 2004
|
