A318881 Restricted growth sequence transform of A277906, the least number with same prime signature as phi(n).

1, 1, 2, 2, 3, 2, 4, 3, 4, 3, 4, 3, 5, 4, 6, 6, 7, 4, 5, 6, 5, 4, 4, 6, 5, 5, 5, 5, 5, 6, 8, 7, 5, 7, 9, 5, 10, 5, 9, 7, 9, 5, 8, 5, 9, 4, 4, 7, 8, 5, 11, 9, 5, 5, 9, 9, 10, 5, 4, 7, 12, 8, 10, 11, 13, 5, 8, 11, 5, 9, 8, 9, 14, 10, 9, 10, 12, 9, 8, 11, 9, 9, 4, 9, 15, 8, 9, 9, 9, 9, 14, 5, 12, 4, 14, 11, 16, 8, 12, 9, 10, 11, 8, 13, 13

Offset: 1

Author

Antti Karttunen, Sep 17 2018

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..65537

Crossrefs

Cf. A000010, A046523, A277906, A319342, A319343, A319344, A319345.

Programs

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; };
A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); }; \\ From A046523
A277906(n) = A046523(eulerphi(n));
v318881 = rgs_transform(vector(up_to,n,A277906(n)));
A318881(n) = v318881[n];