A320109 Filter sequence for counting the residue classes mod 8 of divisors of n.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 3, 11, 5, 12, 13, 14, 15, 16, 3, 17, 13, 6, 7, 18, 19, 10, 20, 21, 5, 22, 7, 23, 20, 24, 13, 25, 5, 6, 13, 26, 15, 22, 3, 11, 27, 12, 7, 28, 29, 30, 20, 17, 5, 31, 13, 32, 20, 10, 3, 33, 5, 12, 34, 35, 36, 31, 3, 37, 13, 22, 7, 38, 15, 10, 39, 11, 13, 22, 7, 40, 41, 24, 3, 33, 36, 6, 13, 18, 15, 42, 13, 21, 13, 12, 13, 43, 15, 44, 45, 46, 5, 31, 7, 26

Offset

1,2

Comments

Restricted growth sequence transform of A320108.

For all i, j: a(i) = a(j) => A320115(i) = A320115(j).

Links

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

Prog

(PARI)
up_to = 100000;
A320108(n) = { my(m=1); fordiv(n, d, if(d>1, m *= prime(1+(d%8)))); (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; };
v320109 = rgs_transform(vector(up_to, n, A320108(n)));
A320109(n) = v320109[n];

Crossrefs

Cf. A320108, A320113, A320115, A320117.

Sequence in context: A351868 A325721 A079050 * A278062 A254597 A064698

Adjacent sequences: A320106 A320107 A320108 * A320110 A320111 A320112

Keyword

nonn

Author

Antti Karttunen, Oct 06 2018

Status

approved