A098372 - OEIS

A098372

a(n) = Max_{k=1..n-1} gcd(n, A098371(k)).

1, 1, 1, 2, 1, 2, 1, 4, 3, 2, 1, 6, 1, 2, 5, 4, 1, 6, 1, 10, 7, 2, 1, 12, 5, 2, 9, 7, 1, 10, 1, 16, 11, 2, 7, 18, 1, 2, 13, 10, 1, 14, 1, 22, 15, 2, 1, 16, 7, 10, 3, 13, 1, 18, 11, 28, 19, 2, 1, 30, 1, 2, 21, 16, 13, 22, 1, 4, 23, 14, 1, 36, 1, 2, 15, 19, 11, 26, 1, 40, 27, 2, 1, 42, 5, 2, 29, 22

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OFFSET

1,4

COMMENTS

From Antti Karttunen, Mar 30 2021: (Start)

The original definition was: a(n) = Max_{k=1..n} gcd(n, A098371(k)).

but this generates terms that differ from ones in the data section at least at n=14, 26, 38, 74, 106.

The original author also commented that: A098371(n) = #{k: a(n) = gcd(n, A098371(k))}, but please see my notes in that sequence.

(End)

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..8192

Antti Karttunen, Data supplement: n, a(n) computed for n = 1..65537

PROG

(PARI) A098372list(up_to) = { my(v=vector(up_to), y=vector(up_to)); v[1] = 1; y[1] = 1; for(n=2, up_to, my(m=1); for(k=1, n-1, m = max(m, gcd(n, v[k]))); y[n] = m; v[n] = sum(k=1, n-1, m == gcd(n, v[k]))); (y); }; \\ Antti Karttunen, Mar 30 2021

CROSSREFS

Cf. A098371.

Sequence in context: A094521 A321757 A159272 * A177236 A341827 A138567

Adjacent sequences: A098369 A098370 A098371 * A098373 A098374 A098375

KEYWORD

nonn,look

AUTHOR

Reinhard Zumkeller, Sep 05 2004

EXTENSIONS

Definition corrected to match with the data. - Antti Karttunen, Mar 30 2021

STATUS

approved