A319338 Filter sequence combining the 2-adic valuation of n (A007814) with gcd(n,sigma(n)) (A009194).

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

Offset

1,2

Comments

Restricted growth sequence transform of ordered pair [A007814(n), A009194(n)].

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; };
A007814(n) = valuation(n, 2);
A009194(n) = gcd(n, sigma(n));
v319338 = rgs_transform(vector(up_to, n, [A007814(n), A009194(n)]));
A319338(n) = v319338[n];

Crossrefs

Cf. A007814, A009194, A305801, A319346.

Sequence in context: A322313 A322315 A375038 * A177815 A007879 A057979

Adjacent sequences: A319335 A319336 A319337 * A319339 A319340 A319341

Keyword

nonn

Author

Antti Karttunen, Sep 24 2018

Status

approved