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 A121368 a(1) = a(2) = 1, a(n) = A007947(a(n-1)) + a(n-2), for n >= 3, i.e., a(n) = a(n-2) plus the largest squarefree divisor of a(n-1). 3
 1, 1, 2, 3, 5, 8, 7, 15, 22, 37, 59, 96, 65, 161, 226, 387, 355, 742, 1097, 1839, 2936, 2573, 5509, 8082, 8203, 16285, 24488, 22407, 46895, 69302, 116197, 185499, 178030, 363529, 541559, 905088, 555701, 1460789, 591330, 2052119, 2643449, 4695568 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Harvey P. Dale, Table of n, a(n) for n = 1..200 EXAMPLE 6 is the largest squarefree divisor of a(12) = 96. So a(13) = 6 + a(11) = 65. MAPLE with(numtheory): A007947 := proc(n) local i, t1, t2; t1 := ifactors(n)[2]; t2 := mul(t1[i][1], i=1..nops(t1)); end: a:=proc(n) if n=1 or n=2 then 1 else A007947(a(n-1))+a(n-2) fi end: seq(a(n), n=1..25); # Emeric Deutsch, Jul 24 2006 MATHEMATICA nxt[{a_, b_}]:={b, a+Max[Select[Divisors[b], SquareFreeQ]]}; NestList[nxt, {1, 1}, 50][[All, 1]] (* Harvey P. Dale, Jan 21 2017 *) CROSSREFS Cf. A007947, A121367, A121369. Sequence in context: A125727 A112337 A141804 * A010073 A264763 A126167 Adjacent sequences:  A121365 A121366 A121367 * A121369 A121370 A121371 KEYWORD nonn AUTHOR Leroy Quet, Jul 23 2006 EXTENSIONS More terms from Emeric Deutsch, Jul 24 2006 More terms from R. J. Mathar, May 18 2007 STATUS approved

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Last modified June 16 13:05 EDT 2021. Contains 345057 sequences. (Running on oeis4.)