A320011 - OEIS

A320011

Filter sequence combined from those proper divisors d of n for which +1 == d (mod 3); Restricted growth sequence transform of A319991.

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

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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: A336664 A335108 A359238 * A068049 A297850 A171092

Adjacent sequences: A320008 A320009 A320010 * A320012 A320013 A320014

KEYWORD

nonn

AUTHOR

Antti Karttunen, Oct 03 2018

STATUS

approved