login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A320012 Filter sequence combined from those proper divisors d of n for which 2 == d (mod 3); Restricted growth sequence transform of A319992. 6
1, 1, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 1, 2, 4, 5, 1, 2, 1, 3, 1, 6, 1, 5, 4, 2, 1, 7, 1, 3, 1, 5, 8, 9, 4, 2, 1, 2, 1, 10, 1, 7, 1, 6, 4, 11, 1, 5, 1, 3, 12, 13, 1, 2, 14, 15, 1, 16, 1, 17, 1, 2, 1, 18, 4, 6, 1, 9, 19, 20, 1, 5, 1, 2, 4, 21, 8, 13, 1, 10, 1, 22, 1, 7, 23, 2, 24, 25, 1, 3, 1, 11, 1, 26, 4, 18, 1, 7, 8, 27, 1, 9, 1, 28, 29 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,4
COMMENTS
For all i, j:
a(i) = a(j) => A320005(i) = A320005(j),
a(i) = a(j) => A293898(i) = A293898(j).
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; };
A019565(n) = {my(j, v); factorback(Mat(vector(if(n, #n=vecextract(binary(n), "-1..1")), j, [prime(j), n[j]])~))}; \\ From A019565
A319992(n) = { my(m=1); fordiv(n, d, if((d<n)&&(2==(d%3)), m *= A019565(d))); m; };
v320012 = rgs_transform(vector(up_to, n, A319992(n)));
A320012(n) = v320012[n];
CROSSREFS
Sequence in context: A087942 A359237 A327925 * A359508 A352825 A241276
KEYWORD
nonn
AUTHOR
Antti Karttunen, Oct 03 2018
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 1 15:57 EDT 2023. Contains 365826 sequences. (Running on oeis4.)