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%I #16 May 07 2021 00:57:23
%S 720,1799,2519,2520,3240,4319,5039,5040,5760,6839,7559,7560,8280,9359,
%T 10079,10080,10800,11879,12599,12600,13320,14399,15119,15120,15840,
%U 16919,17639,17640,18360,19439,20159,20160,20880,21959,22679,22680,23400,24479,25199,25200,25920
%N Numbers k such that either k or k+1 is divisible by the numbers from 1 to 10.
%C Also numbers k such that 2520 | k*(k+1). - _David A. Corneth_, May 06 2021
%H David A. Corneth, <a href="/A131663/b131663.txt">Table of n, a(n) for n = 1..10000</a> (first 1001 terms from Harvey P. Dale)
%F a(n) = 2520 + a(n-4), n >= 5. - _David A. Corneth_, May 06 2021
%e 720 is divisible by 2, 3, 4, 5, 6, 8, 9 and 10; while 721 is divisible by 7.
%t Select[Range[30000], Mod[ #, 8]*Mod[ # + 1, 8] == 0 && Mod[ #, 9]*Mod[ # + 1, 9] == 0 && Mod[ #, 5]*Mod[ # + 1, 5] == 0 && Mod[ #, 7]*Mod[ # + 1, 7] == 0 && Mod[ #, 8]*Mod[ # + 1, 8] == 0 && Mod[ #, 6]*Mod[ # + 1, 6] == 0 && Mod[ #, 10]*Mod[ # + 1, 10] == 0 &]
%t Select[Range[23000],Take[Union[Join[Divisors[#],Divisors[#+1]]],10] == Range[ 10]&]// Quiet (* _Harvey P. Dale_, Jul 03 2020 *)
%o (PARI) first(n) = { my(res = List([720, 1799, 2519, 2520])); for(i = 5, n, listput(res, res[i-4]+2520)); res } \\ _David A. Corneth_, May 06 2021
%Y Cf. A002378.
%K nonn,easy
%O 1,1
%A _Tanya Khovanova_, Sep 13 2007
%E Offset changed to 1 by _David A. Corneth_, May 06 2021
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