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 A051539 a(n) = least common multiple of {1, 5, 9, 13, 17 ..., 4n+1} (A016813). 8
 1, 5, 45, 585, 9945, 69615, 348075, 10094175, 111035925, 4108329225, 168441498225, 168441498225, 1179090487575, 62491795841475, 1187344120988025, 72427991380269525, 72427991380269525, 1665843801746199075, 121606597527472532475, 121606597527472532475 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS This sequence coincides with sequence A097328 of denominators of 1+1/5+1/9+1/13+...+1/(4n+1) iff n<12. - T. D. Noe, Aug 04 2004 LINKS Harvey P. Dale, Table of n, a(n) for n = 0..866 (* First 201 terms from T.D. Noe *) EXAMPLE a(3) = LCM {1, 5, 9, 13} = 585 MATHEMATICA Table[ Apply[ LCM, Join[{1}, Table[1 + 4i, {i, 0, n}]]], {n, 0, 19}] nn=20; Table[LCM@@Take[4Range[0, nn-1]+1, n], {n, nn}] (* Harvey P. Dale, Jul 04 2011 *) Table[LCM@@NestList[#+4&, 1, n], {n, 0, 20}] (* Harvey P. Dale, Nov 21 2016 *) PROG (MAGMA) k:=77; [Lcm([h: h in [1..j by 4]]): j in [1..k by 4]];  // Bruno Berselli, May 03 2011 (PARI) a(n)=lcm(vector(n, i, 4*n+1)) \\ Charles R Greathouse IV, Feb 09 2017 CROSSREFS Cf. A016813, A075136, A074598, A097329. Sequence in context: A121414 A243678 A097328 * A007696 A090136 A090356 Adjacent sequences:  A051536 A051537 A051538 * A051540 A051541 A051542 KEYWORD easy,nice,nonn AUTHOR Asher Auel (asher.auel(AT)reed.edu) EXTENSIONS Edited by Robert G. Wilson v, Aug 27 2002 a(16) corrected by T. D. Noe, Feb 08 2008 STATUS approved

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Last modified March 26 18:36 EDT 2019. Contains 321511 sequences. (Running on oeis4.)