This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A003990 Table of lcm(x,y), read along antidiagonals. 24
 1, 2, 2, 3, 2, 3, 4, 6, 6, 4, 5, 4, 3, 4, 5, 6, 10, 12, 12, 10, 6, 7, 6, 15, 4, 15, 6, 7, 8, 14, 6, 20, 20, 6, 14, 8, 9, 8, 21, 12, 5, 12, 21, 8, 9, 10, 18, 24, 28, 30, 30, 28, 24, 18, 10, 11, 10, 9, 8, 35, 6, 35, 8, 9, 10, 11, 12, 22, 30, 36, 40, 42, 42, 40, 36, 30, 22, 12, 13, 12, 33, 20, 45, 24 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS A(x,x) = x on the diagonal. - Reinhard Zumkeller, Aug 05 2012 LINKS T. D. Noe, First 100 antidiagonals of array, flattened Kival Ngaokrajang, Illustration of pattern, where terms with least significant decimal digit equal to zero are colored. EXAMPLE The symmetric array is lcm(x,y) = lcm(y,x):    1  2  3  4  5  6  7  8  9 10 ...    2  2  6  4 10  6 14  8 18 10 ...    3  6  3 12 15  6 21 24  9 30 ...    4  4 12  4 20 12 28  8 36 20 ...    5 10 15 20  5 30 35 40 45 10 ...    6  6  6 12 30  6 42 24 18 30 ...    7 14 21 28 35 42  7 56 63 70 ...    8  8 24  8 40 24 56  8 72 40 ...    9 18  9 36 45 18 63 72  9 90 ...   10 10 30 20 10 30 70 40 90 10 ... MATHEMATICA Table[ LCM[x-y, y], {x, 1, 14}, {y, 1, x-1}] // Flatten (* Jean-François Alcover, Aug 20 2013 *) PROG (Haskell) a003990 x y = a003990_adiag x !! (y-1) a003990_adiag n = a003990_tabl !! (n-1) a003990_tabl = zipWith (zipWith lcm) a002260_tabl \$ map reverse a002260_tabl -- Reinhard Zumkeller, Aug 05 2012 (PARI) A(x, y)=lcm(x, y) \\ Charles R Greathouse IV, Feb 06 2017 CROSSREFS Cf. A003989, A003991, A051173. A(x, y) = A075174(A003986(A075173(x), A075173(y))) = A075176(A003986(A075175(x), A075175(y))). Antidiagonal sums are in A006580. Cf. A002260. Sequence in context: A045772 A294977 A091256 * A287958 A059896 A079542 Adjacent sequences:  A003987 A003988 A003989 * A003991 A003992 A003993 KEYWORD tabl,nonn,easy,nice,look AUTHOR STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified November 13 00:33 EST 2018. Contains 317118 sequences. (Running on oeis4.)