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A305425 a(n) = n/2 for even n, a(n) = A305422(n) for odd n. 4
1, 1, 2, 2, 4, 3, 3, 4, 6, 5, 7, 6, 11, 7, 8, 8, 16, 9, 13, 10, 5, 11, 22, 12, 19, 13, 12, 14, 14, 15, 25, 16, 50, 17, 29, 18, 31, 19, 28, 20, 37, 21, 38, 22, 24, 23, 41, 24, 9, 25, 32, 26, 26, 27, 47, 28, 44, 29, 55, 30, 59, 31, 10, 32, 20, 33, 61, 34, 21, 35, 118, 36, 67, 37, 88, 38, 110, 39, 53, 40, 69, 41, 18, 42, 64, 43, 73, 44, 94, 45, 87, 46, 43, 47 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
Each k occurs exactly twice, at 2k and at A305421(k).
LINKS
FORMULA
a(n) = n/2 if n is even, a(n) = A305422(n) if n is odd.
PROG
(PARI)
A091225(n) = polisirreducible(Pol(binary(n))*Mod(1, 2));
A305419(n) = if(n<3, 1, my(k=n-1); while(k>1 && !A091225(k), k--); (k));
A305422(n) = { my(f = subst(lift(factor(Pol(binary(n))*Mod(1, 2))), x, 2)); for(i=1, #f~, f[i, 1] = Pol(binary(A305419(f[i, 1])))); fromdigits(Vec(factorback(f))%2, 2); };
A305425(n) = if(n%2, A305422(n), n/2);
CROSSREFS
Bisections: A000027 and A305422.
Cf. also A252463.
Sequence in context: A292421 A205563 A147594 * A212652 A303691 A205678
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jun 08 2018
STATUS
approved

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Last modified June 24 02:53 EDT 2024. Contains 373661 sequences. (Running on oeis4.)