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 A090637 Trajectory of 28 under the map k -> A003415(k) (taking the arithmetic derivative). 3
 28, 32, 80, 176, 368, 752, 1520, 3424, 8592, 20096, 70464, 235072, 705280, 3023616, 13223680, 55540736, 278539264, 1392697344, 9541095424, 58609614848, 410267320320, 3397142953984, 24143851798528, 176071227916288, 1232666139967488, 9523075842834432 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Equals A090636 from a(2) = 32 = A090636(5) on. See there and A090635 for more. LINKS Alois P. Heinz, Table of n, a(n) for n = 1..100 EXAMPLE a(2) = 28' = (2^2*7)' = 28*(2/2 + 1/7) = 32. MAPLE a:= proc(n) option remember; `if`(n=1, 28, (t-> t*add(i[2]/i[1], i=ifactors(t)[2]))(a(n-1))) end: seq(a(n), n=1..31); # Alois P. Heinz, Dec 02 2019 PROG (PARI) a(n)=A090636(n, 28) CROSSREFS Cf. A090636, A090635. Sequence in context: A232727 A232766 A230855 * A261113 A280649 A134657 Adjacent sequences: A090634 A090635 A090636 * A090638 A090639 A090640 KEYWORD nonn AUTHOR N. J. A. Sloane, Dec 14 2003 EXTENSIONS Edited by M. F. Hasler, Nov 27 2019 STATUS approved

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Last modified February 25 16:57 EST 2024. Contains 370332 sequences. (Running on oeis4.)