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A182558

a(n) = a(n-1)*2 - floor(sqrt(a(n-2))).

0, 1, 2, 3, 5, 9, 16, 29, 54, 103, 199, 388, 762, 1505, 2983, 5928, 11802, 23528, 46948, 93743, 187270, 374234, 748036, 1495461, 2990058, 5978894, 11956059, 23909673, 47815889, 95626889, 191246864, 382483950, 764954071, 1529888585, 3059749513, 6119459913, 12238864511

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,3

LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..1000

FORMULA

a(0)=0, a(1)=1, a(n) = a(n-1)*2 - floor(sqrt(a(n-2))).

MATHEMATICA

nxt[{a_, b_}]:={b, 2b-Floor[Sqrt[a]]}; NestList[nxt, {0, 1}, 40][[All, 1]] (* Harvey P. Dale, Apr 29 2017 *)

PROG

(Python)

import math