A320011 Filter sequence combined from those proper divisors d of n for which +1 == d (mod 3); Restricted growth sequence transform of A319991.
1, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 3, 2, 4, 2, 3, 2, 2, 2, 5, 4, 2, 2, 3, 2, 6, 2, 7, 2, 8, 2, 9, 2, 2, 4, 3, 2, 10, 6, 5, 2, 4, 2, 11, 2, 2, 2, 9, 4, 12, 2, 13, 2, 2, 2, 14, 10, 2, 2, 5, 2, 15, 4, 9, 6, 16, 2, 17, 2, 18, 2, 3, 2, 19, 20, 21, 4, 6, 2, 22, 2, 2, 2, 14, 2, 23, 2, 11, 2, 8, 24, 25, 15, 2, 10, 9, 2, 26, 2, 27, 2, 28, 2, 29, 4
Offset: 1
Keywords
Links
- Antti Karttunen, Table of n, a(n) for n = 1..65537
Programs
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PARI
up_to = 65537; 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; }; A019565(n) = {my(j,v); factorback(Mat(vector(if(n, #n=vecextract(binary(n), "-1..1")), j, [prime(j), n[j]])~))}; \\ From A019565 A319991(n) = { my(m=1); fordiv(n,d,if((d
A019565(d))); m; }; v320011 = rgs_transform(vector(up_to,n,A319991(n))); A320011(n) = v320011[n];
Comments