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A309816 a(n) is the 2-adic valuation of A014664(n). 0
1, 2, 0, 1, 2, 3, 1, 0, 2, 0, 2, 2, 1, 0, 2, 1, 2, 1, 0, 0, 0, 1, 0, 4, 2, 0, 1, 2, 2, 0, 1, 2, 1, 2, 0, 2, 1, 0, 2, 1, 2, 0, 5, 2, 0, 1, 0, 1, 2, 0, 0, 3, 1, 4, 0, 2, 0, 2, 1, 1, 2, 1, 0, 2, 2, 1, 0, 1, 2, 3, 0, 0, 2, 1, 0, 2, 2, 3, 2, 1, 2, 0, 3, 0, 1, 5, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

COMMENTS

Let p and q be distinct odd primes. Then there exists an integer i such that 2^i == -1 (mod p*q) if and only if a(u) = a(v) and a(u), a(v) > 0, where u and v are the indices of p and q in A000040, respectively (cf. Anderson, Preece, 2008, Lemma 1.4).

LINKS

Table of n, a(n) for n=2..88.

I. Anderson and D. A. Preece, A general approach to constructing power-sequence terraces for Z_n, Discrete Mathematics, Vol. 308, No. 5-6 (2008), 631-644.

EXAMPLE

For n = 7: A014664(7) = 8 and the 2-adic valuation of 8 is 3, since 2^3 = 8, so a(7) = 3.

PROG

(PARI) a014664(n) = my(p=prime(n)); znorder(Mod(2, p))

a(n) = valuation(a014664(n), 2)

CROSSREFS

Cf. A000040, A014664.

Sequence in context: A117398 A295989 A240852 * A071486 A046695 A071433

Adjacent sequences:  A309813 A309814 A309815 * A309817 A309818 A309819

KEYWORD

nonn,easy

AUTHOR

Felix Fröhlich, Aug 18 2019

STATUS

approved

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Last modified February 24 21:04 EST 2020. Contains 332210 sequences. (Running on oeis4.)