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A318881
Restricted growth sequence transform of A277906, the least number with same prime signature as phi(n).
5
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
1,3
LINKS
PROG
(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];
KEYWORD
nonn
AUTHOR
Antti Karttunen, Sep 17 2018
STATUS
approved