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A341353
Greatest k such that 3^k divides A156552(n); the 3-adic valuation of A156552(n).
9
0, 0, 1, 0, 0, 0, 0, 1, 2, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 2, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 3, 0, 0, 1, 1, 0, 0, 0, 0, 0, 3, 0, 0, 1, 0, 0, 0, 0, 0, 2, 0, 1, 0, 0, 0, 0, 1, 0, 2, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 0, 3, 3, 0, 2, 2, 0, 0, 2, 0, 0, 0, 0, 0, 1, 0, 2, 0, 0
OFFSET
2,9
FORMULA
a(n) = A007949(A156552(n)).
a(p) = 0 for all primes p.
a(n^2) > 0 for all n >= 2.
a(n) > 0 iff A329903(n) = 0.
PROG
(PARI)
A007949(n) = valuation(n, 3);
A156552(n) = { my(f = factor(n), p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res };
CROSSREFS
Cf. A007949, A156552, A329609 (positions of nonzeros), A329903, A341354 (even bisection), A341355.
Cf. also A055396 (the 2-adic valuation + 1), A292251.
Sequence in context: A080224 A341508 A261488 * A010105 A341618 A337690
KEYWORD
nonn
AUTHOR
Antti Karttunen, Feb 14 2021
STATUS
approved