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A217793
Erdős-Turán Golomb rulers, triangle read by rows.
2
0, 7, 13, 0, 11, 24, 34, 41, 0, 15, 32, 44, 58, 74, 85, 0, 23, 48, 75, 93, 113, 135, 159, 185, 202, 221, 0, 27, 56, 87, 107, 142, 166, 192, 220, 237, 269, 290, 313, 0, 35, 72, 111, 152, 178, 206, 253, 285, 319, 355, 376, 416, 458, 485, 514, 545, 0, 39, 80
OFFSET
1,2
LINKS
P. Erdős and P. Turán, On a problem of Sidon in additive number theory, and on some related problems, J. Lond. Math. Soc. 16 (1941), 212-215.
Eric Weisstein's World of Mathematics, Golomb Ruler.
Wikipedia, Golomb ruler
FORMULA
T(n,k) = 2*p*k + k^2 mod p with p = n-th odd prime and 0 <= k < p.
EXAMPLE
First rows:
. 1 0,7,13
. 2 0,11,24,34,41
. 3 0,15,32,44,58,74,85
. 4 0,23,48,75,93,113,135,159,185,202,221
. 5 0,27,56,87,107,142,166,192,220,237,269,290,313
. 6 0,35,72,111,152,178,206,253,285,319,355,376,416,458,485,514,545 .
PROG
(Haskell)
a217793 n k = a217793_tabf !! (n-1) !! k
a217793_row n = a217793_tabf !! (n-1)
a217793_tabf =
map (\p -> [2*p*k + k^2 `mod` p | k <- [0..p-1]]) a065091_list
CROSSREFS
Cf. A065091 (row lengths).
Sequence in context: A157808 A354301 A225227 * A299472 A285642 A209189
KEYWORD
nonn,tabf
AUTHOR
Reinhard Zumkeller, Mar 25 2013
STATUS
approved