A230215 Numbers divisible by 3 or 13.
3, 6, 9, 12, 13, 15, 18, 21, 24, 26, 27, 30, 33, 36, 39, 42, 45, 48, 51, 52, 54, 57, 60, 63, 65, 66, 69, 72, 75, 78, 81, 84, 87, 90, 91, 93, 96, 99, 102, 104, 105, 108, 111, 114, 117, 120, 123, 126, 129, 130, 132, 135, 138, 141, 143, 144, 147, 150, 153, 156
Offset: 1
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
- Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,0,0,0,0,0,0,0,0,0,1,-1).
Programs
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Maple
for n from 1 to 138 do if n mod 3 = 0 or n mod 13= 0 then print(n) fi od
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Mathematica
Select[Range[200], GCD[#, 39] > 1 &] (* T. D. Noe, Oct 15 2013 *) With[{nn=60},Join[3*Range[nn],13*Floor[3/13 Range[nn]]]]//Union//Rest (* Harvey P. Dale, May 25 2020 *)
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PARI
is(n)=gcd(n,39)>1 \\ Charles R Greathouse IV, Dec 11 2013
Formula
a(n+15) = a(n) + 39.
Comments