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A322973
Lexicographically earliest such sequence a that a(i) = a(j) => f(i) = f(j) for all i, j, where f(1) = 0, f(n) = -1 if n is an odd prime, and f(n) = A006370(n) for all other numbers.
3
1, 2, 3, 4, 3, 5, 3, 6, 7, 8, 3, 9, 3, 10, 11, 12, 3, 13, 3, 14, 15, 16, 3, 17, 18, 19, 20, 21, 3, 22, 3, 23, 24, 25, 26, 27, 3, 28, 29, 30, 3, 31, 3, 32, 33, 34, 3, 35, 36, 37, 38, 39, 3, 40, 41, 7, 42, 43, 3, 44, 3, 45, 46, 47, 48, 49, 3, 50, 51, 52, 3, 53, 3, 54, 55, 56, 57, 58, 3, 59, 60, 61, 3, 62, 63, 64, 65, 66, 3, 67, 68, 11, 69, 70, 71, 72, 3, 73, 74, 75, 3, 76, 3
OFFSET
1,2
COMMENTS
For all i, j: a(i) = a(j) => A274472(i) = A274472(j).
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; };
A006370(n) = if(n%2, 3*n+1, n/2);
A322973aux(n) = if(1==n, 0, if((n>2)&&isprime(n), -1, A006370(n)));
v322973 = rgs_transform(vector(up_to, n, A322973aux(n)));
A322973(n) = v322973[n];
CROSSREFS
See the crossrefs section in A322809 for a list of similarly constructed filter sequences.
Sequence in context: A353520 A361021 A373980 * A305890 A305801 A075850
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jan 05 2019
STATUS
approved