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A286386 Compound filter: a(n) = 2*A286473(n) + (1 if n is a square, 0 otherwise). 2
3, 12, 14, 21, 10, 28, 14, 36, 31, 44, 14, 52, 10, 60, 46, 69, 10, 76, 14, 84, 62, 92, 14, 100, 43, 108, 78, 116, 10, 124, 14, 132, 94, 140, 58, 149, 10, 156, 110, 164, 10, 172, 14, 180, 126, 188, 14, 196, 63, 204, 142, 212, 10, 220, 90, 228, 158, 236, 14, 244, 10, 252, 174, 261, 106, 268, 14, 276, 190, 284, 14, 292, 10, 300, 206, 308, 94, 316, 14, 324, 223 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = 2*A286473(n) + A010052(n).

PROG

(Scheme) (define (A286386 n) (+ (* 2 (A286473 n)) (A010052 n)))

(Python)

from sympy import sqrt, divisors, primefactors

import math

def a010052(n): return 1 if n<1 else int(math.floor(sqrt(n))) - int(math.floor(sqrt(n - 1)))

def a286473(n): return 1 if n==1 else 4*divisors(n)[-2] + (min(primefactors(n))%4)

def a(n): return 2*a286473(n) + a010052(n) # Indranil Ghosh, May 14 2017

CROSSREFS

Cf. A000290 (gives the positions off odd terms), A010052, A286473, A286366, A286388.

Sequence in context: A222711 A176796 A242130 * A032918 A039945 A227302

Adjacent sequences:  A286383 A286384 A286385 * A286387 A286388 A286389

KEYWORD

nonn

AUTHOR

Antti Karttunen, May 13 2017

STATUS

approved

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Last modified February 19 13:23 EST 2018. Contains 299333 sequences. (Running on oeis4.)