login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A336313
Lexicographically earliest infinite sequence such that a(i) = a(j) => A278222(A336125(i)) = A278222(A336125(j)) for all i, j >= 1.
4
1, 2, 2, 2, 2, 2, 2, 3, 3, 2, 2, 3, 2, 2, 3, 3, 2, 2, 2, 3, 3, 2, 2, 3, 2, 2, 4, 3, 2, 2, 2, 3, 3, 2, 2, 5, 2, 2, 3, 3, 2, 2, 2, 3, 4, 2, 2, 3, 3, 3, 3, 3, 2, 2, 2, 3, 3, 2, 2, 5, 2, 2, 4, 5, 2, 2, 2, 3, 3, 3, 2, 5, 2, 2, 3, 3, 3, 2, 2, 3, 6, 2, 2, 5, 2, 2, 3, 3, 2, 2, 3, 3, 3, 2, 2, 5, 2, 2, 4, 3, 2, 2, 2, 3, 3
OFFSET
1,2
COMMENTS
Restricted growth sequence transform of A278222(A336125(n)).
For all i, j: A336311(i) = A336311(j) => a(i) = a(j) => A336123(i) = A336123(j).
LINKS
PROG
(PARI)
\\ Needs also code from A336124:
up_to = 1024; \\ 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; };
A253553(n) = if(n<=2, 1, my(f=factor(n), k=#f~); if(f[k, 2]>1, f[k, 2]--, f[k, 1] = precprime(f[k, 1]-1)); factorback(f));
A336125(n) = if(n<=2, n-1, (1==A336124(n))+(2*A336125(A253553(n))));
A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); t }; \\ From A005940
A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); }; \\ From A046523
A278222(n) = A046523(A005940(1+n));
v336313 = rgs_transform(vector(up_to, n, A278222(A336125(n))));
A336313(n) = v336313[n];
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jul 17 2020
STATUS
approved