A295877 Restricted growth sequence transform of A173557, Product_{p|n} (p-1).

1, 1, 2, 1, 3, 2, 4, 1, 2, 3, 5, 2, 6, 4, 7, 1, 8, 2, 9, 3, 6, 5, 10, 2, 3, 6, 2, 4, 11, 7, 12, 1, 13, 8, 14, 2, 15, 9, 14, 3, 16, 6, 17, 5, 7, 10, 18, 2, 4, 3, 19, 6, 20, 2, 16, 4, 15, 11, 21, 7, 22, 12, 6, 1, 23, 13, 24, 8, 25, 14, 26, 2, 27, 15, 7, 9, 22, 14, 28, 3, 2, 16, 29, 6, 30, 17, 31, 5, 32, 7, 27, 10, 22, 18, 27, 2, 33, 4, 13, 3, 34, 19, 35, 6, 23

Offset: 1

Author

Antti Karttunen, Nov 29 2017

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..65536

Crossrefs

Cf. A173557, A295876.

Programs

PARI

allocatemem(2^30);
up_to = 65536;
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; };
write_to_bfile(start_offset,vec,bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }
A173557(n) = my(f=factor(n)[, 1]); prod(k=1, #f, f[k]-1); \\ This function from Michel Marcus, Oct 31 2017
write_to_bfile(1,rgs_transform(vector(up_to,n,A173557(n))),"b295877.txt");

Formula

a(2n) = a(n).