A320115 Filter sequence for counting the residue classes mod 4 of divisors of n.

1, 2, 3, 4, 5, 6, 3, 7, 8, 9, 3, 10, 5, 6, 11, 12, 5, 13, 3, 14, 11, 6, 3, 15, 16, 9, 11, 10, 5, 17, 3, 18, 11, 9, 11, 19, 5, 6, 11, 20, 5, 17, 3, 10, 21, 6, 3, 22, 8, 23, 11, 14, 5, 17, 11, 15, 11, 9, 3, 24, 5, 6, 25, 26, 27, 17, 3, 14, 11, 17, 3, 28, 5, 9, 25, 10, 11, 17, 3, 29, 30, 9, 3, 24, 27, 6, 11, 15, 5, 31, 11, 10, 11, 6, 11, 32, 5, 13, 25, 33, 5, 17, 3, 20

Offset

1,2

Comments

Restricted growth sequence transform of A320114.

For all i, j:

A319994(i) = A319994(j) => a(i) = a(j),

A320004(i) = A320004(j) => a(i) = a(j),

a(i) = a(j) => A002654(i) = A002654(j).

Links

Antti Karttunen, Table of n, a(n) for n = 1..100000

Prog

(PARI)
up_to = 100000;
A320114(n) = { my(m=1); fordiv(n, d, if(d>1, m *= prime(1+(d%4)))); (m); };
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; };
v320115 = rgs_transform(vector(up_to, n, A320114(n)));
A320115(n) = v320115[n];

Crossrefs

Cf. A319994, A320004, A320109, A320113, A320114, A320117.

Sequence in context: A323081 A274630 A278058 * A319994 A319714 A320004

Adjacent sequences: A320112 A320113 A320114 * A320116 A320117 A320118

Keyword

nonn

Author

Antti Karttunen, Oct 06 2018

Status

approved