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 A141766 A positive integer n is included if both (p-1) and (p+1) divide n for every prime p that divides n. 4
 1, 12, 24, 36, 48, 60, 72, 96, 108, 120, 144, 168, 180, 192, 216, 240, 288, 300, 324, 336, 360, 384, 432, 480, 504, 540, 576, 600, 648, 660, 672, 720, 768, 840, 864, 900, 960, 972, 1008, 1080, 1152, 1176, 1200, 1296, 1320, 1344, 1440, 1500, 1512, 1536, 1620 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Every term is a multiple of 12. LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..1000 EXAMPLE 120 has the prime factorization of 2^3 * 3^1 * 5^1. The distinct primes dividing 120 are therefore 2,3,5. 2-1=1, 3-1=2 and 5-1=4 all divide 120. Also, 2+1=3, 3+1=4 and 5+1=6 all divide 120. So 120 is included in the sequence. MATHEMATICA Select[Range[2, 1620], Function[n, AllTrue[FactorInteger[n][[All, 1]], AllTrue[# + {-1, 1}, Divisible[n, #] &] &]]] (* Michael De Vlieger, Sep 22 2017 *) PROG (Haskell) a141766 n = a141766_list !! (n-1) a141766_list = filter f [1..] where    f x = all (== 0) \$ map (mod x) \$ (map pred ps) ++ (map succ ps)          where ps = a027748_row x -- Reinhard Zumkeller, Aug 27 2013 CROSSREFS Cf. A140470, A141767, A124240. Cf. A027748. Sequence in context: A044837 A033009 A140470 * A069056 A019550 A117304 Adjacent sequences:  A141763 A141764 A141765 * A141767 A141768 A141769 KEYWORD nonn AUTHOR Leroy Quet, Jul 02 2008 EXTENSIONS a(12)-a(50) from Donovan Johnson, Sep 27 2008 a(1)=1 prepended by Max Alekseyev, Aug 27 2013 STATUS approved

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Last modified September 23 10:55 EDT 2021. Contains 347612 sequences. (Running on oeis4.)