OFFSET
1,2
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..65535
PROG
(PARI)
up_to = (2^16)+1;
v281978 = vector(1+up_to); v281978[1] = 1;
minverses = Map(); mapput(minverses, 1, 1);
least_unused_proper_divisor(inverses, n) = { fordiv(n, d, if((d<n) && !mapisdefined(minverses, d), return(d))); (0); }
prev=1; n = 2; while(n < up_to+1, try = prev; while(mapisdefined(minverses, try) || !(pd = least_unused_proper_divisor(minverses, try)), try += prev); mapput(minverses, v281978[n] = try, n); mapput(minverses, v281978[1+n] = pd, 1+n); prev = pd; n += 2);
A281978(n) = v281978[n];
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
A304730(n) = v304730[n];
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, May 19 2018
STATUS
approved