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A320011 Filter sequence combined from those proper divisors d of n for which +1 == d (mod 3); Restricted growth sequence transform of A319991. 6
1, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 3, 2, 4, 2, 3, 2, 2, 2, 5, 4, 2, 2, 3, 2, 6, 2, 7, 2, 8, 2, 9, 2, 2, 4, 3, 2, 10, 6, 5, 2, 4, 2, 11, 2, 2, 2, 9, 4, 12, 2, 13, 2, 2, 2, 14, 10, 2, 2, 5, 2, 15, 4, 9, 6, 16, 2, 17, 2, 18, 2, 3, 2, 19, 20, 21, 4, 6, 2, 22, 2, 2, 2, 14, 2, 23, 2, 11, 2, 8, 24, 25, 15, 2, 10, 9, 2, 26, 2, 27, 2, 28, 2, 29, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

For all i, j:

  a(i) = a(j) => A320001(i) = A320001(j),

  a(i) = a(j) => A293897(i) = A293897(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

A319991(n) = { my(m=1); fordiv(n, d, if((d<n)&&(1==(d%3)), m *= A019565(d))); m; };

v320011 = rgs_transform(vector(up_to, n, A319991(n)));

A320011(n) = v320011[n];

CROSSREFS

Cf. A293223, A319991, A320010, A320012, A320013, A320014.

Sequence in context: A096917 A336664 A335108 * A068049 A297850 A171092

Adjacent sequences:  A320008 A320009 A320010 * A320012 A320013 A320014

KEYWORD

nonn

AUTHOR

Antti Karttunen, Oct 03 2018

STATUS

approved

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Last modified September 27 19:34 EDT 2021. Contains 347694 sequences. (Running on oeis4.)