OFFSET
1,8
COMMENTS
LINKS
PROG
(PARI)
up_to = 20000;
A020639(n) = if(1==n, n, vecmin(factor(n)[, 1]));
ordinal_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), pt); for(i=1, length(invec), if(mapisdefined(om, invec[i]), pt = mapget(om, invec[i]), pt = 0); outvec[i] = (1+pt); mapput(om, invec[i], (1+pt))); outvec; };
v078898 = ordinal_transform(vector(up_to, n, A020639(n)));
A078898(n) = v078898[n];
CROSSREFS
KEYWORD
sign
AUTHOR
Antti Karttunen, Nov 27 2021
STATUS
approved