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A319338 Filter sequence combining the 2-adic valuation of n (A007814) with gcd(n,sigma(n)) (A009194). 3
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 (list; graph; refs; listen; history; text; internal format)
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: A228179 A322313 A322315 * A177815 A007879 A057979

Adjacent sequences:  A319335 A319336 A319337 * A319339 A319340 A319341

KEYWORD

nonn

AUTHOR

Antti Karttunen, Sep 24 2018

STATUS

approved

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Last modified September 28 04:24 EDT 2021. Contains 347698 sequences. (Running on oeis4.)