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A320010 Filter sequence combined from those proper divisors of n that are multiples of 3; Restricted growth sequence transform of A319990. 5
1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 3, 1, 1, 2, 1, 1, 4, 1, 1, 2, 1, 1, 5, 1, 1, 6, 1, 1, 7, 1, 1, 2, 1, 1, 8, 1, 1, 2, 1, 1, 9, 1, 1, 10, 1, 1, 11, 1, 1, 2, 1, 1, 12, 1, 1, 2, 1, 1, 13, 1, 1, 14, 1, 1, 15, 1, 1, 2, 1, 1, 16, 1, 1, 4, 1, 1, 17, 1, 1, 18, 1, 1, 19, 1, 1, 2, 1, 1, 20, 1, 1, 2, 1, 1, 21, 1, 1, 22, 1, 1, 23, 1, 1, 24 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

COMMENTS

For all i, j: a(i) = a(j) => A320003(i) = A320003(j).

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..65537

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

A319990(n) = { my(m=1); fordiv(n, d, if((d<n)&&(0==(d%3)), m *= A019565(d))); m; };

v320010 = rgs_transform(vector(up_to, n, A319990(n)));

A320010(n) = v320010[n];

CROSSREFS

Cf. A319990, A320011, A320012, A320014.

Sequence in context: A280509 A153096 A343407 * A210763 A281681 A218799

Adjacent sequences:  A320007 A320008 A320009 * A320011 A320012 A320013

KEYWORD

nonn

AUTHOR

Antti Karttunen, Oct 03 2018

STATUS

approved

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Last modified September 24 06:13 EDT 2021. Contains 347623 sequences. (Running on oeis4.)