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A256566 a(n) is the central term of the (2n-1)-st row of triangle A256440. 1
1, 3, 3, 3, 9, 9, 9, 2, 2, 2, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 38, 46, 46, 46, 46, 46, 46, 58, 58, 58, 58, 58, 58, 58, 58, 58, 58, 58, 58, 62, 62, 74, 74, 74, 74, 82, 82, 74, 74, 74, 62, 74, 74, 74, 74, 74, 62, 74, 74, 82, 82, 82, 82, 82, 82, 82 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

All terms are deficient and after the 4th term sigma(n)/n appears to stay between 1.5 and 1.6.

Note that sequence is not monotonic and can return later to previous terms values.

LINKS

Michel Marcus, Table of n, a(n) for n = 1..1000

PROG

(PARI) lista(nn) = {forstep(n=1, nn, 2, v = vector(n, k, sigma(k)/k); w = vecsort(v, , 1); print1(w[(n+1)/2], ", "); ); }

CROSSREFS

Cf. A005100 (deficient numbers), A256440.

Sequence in context: A217547 A285583 A253358 * A132171 A304682 A217645

Adjacent sequences:  A256563 A256564 A256565 * A256567 A256568 A256569

KEYWORD

nonn

AUTHOR

Michel Marcus, Apr 02 2015

STATUS

approved

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Last modified January 17 18:00 EST 2020. Contains 330987 sequences. (Running on oeis4.)