cp's OEIS Frontend

A291766 Restricted growth sequence transform of A291755; filter combining multiplicative order of 2 mod 2n+1 & eulerphi(2n+1) (A002326 & A037225).

%I A291766 #9 Oct 02 2017 18:58:27
%S A291766 1,2,3,4,5,6,7,8,9,10,11,12,13,10,14,15,16,17,18,17,19,20,17,21,22,23,
%T A291766 24,19,25,26,27,28,29,30,31,32,33,19,34,35,36,37,38,39,40,41,42,43,44,
%U A291766 34,45,46,29,47,48,43,49,50,41,51,52,53,45,54,55,56,57,43,58,59,60,61,49,62,63,64,51,65,66,67,68,69,53,70,71,57,72,61,73,74,75,61
%N A291766 Restricted growth sequence transform of A291755; filter combining multiplicative order of 2 mod 2n+1 & eulerphi(2n+1) (A002326 & A037225).
%H A291766 Antti Karttunen, <a href="/A291766/b291766.txt">Table of n, a(n) for n = 0..32768</a>
%o A291766 (PARI)
%o A291766 rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
%o A291766 write_to_bfile(start_offset,vec,bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }
%o A291766 A002326(n) = if(n<0, 0, znorder(Mod(2, 2*n+1))); \\ This function from _Michael Somos_, Mar 31 2005
%o A291766 A291755(n) = (1/2)*(2 + ((A002326(n)+eulerphi(n+n+1))^2) - A002326(n) - 3*eulerphi(n+n+1));
%o A291766 write_to_bfile(0,rgs_transform(vector(32769,n,A291755(n-1))),"b291766_upto32768.txt");
%Y A291766 Cf. A000010, A002326, A037225, A291755.
%Y A291766 Cf. A291769, A292267 for related filters.
%Y A291766 Cf. A037226, A053006.
%K A291766 nonn
%O A291766 0,2
%A A291766 _Antti Karttunen_, Oct 02 2017