# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/

Search: id:a038389
Showing 1-1 of 1

%I A038389 #25 Feb 12 2018 16:40:05
%S A038389 1,2,3,4,5,6,7,5,5,10,11,12,13,14,15,10,17,10,19,20,21,22,23,15,13,26,
%T A038389 15,28,29,30,31,17,33,34,35,20,37,38,39,25,41,42,43,44,25,46,47,30,25,
%U A038389 26,51,52,53,30,55,35,57,58,59,60,61,62,35,34,65,66,67,68,69,70,71,37,73,74,39,76,77,78
%N A038389 Let f(n) be the smallest number such that the arithmetic mean (A) and geometric mean (G) of n and f(n) are both integers; sequence gives A values.
%C A038389 It is the average of A038387 with n, both of which are multiplicative. - _Christian G. Bower_, May 16 2005
%C A038389 However, this sequence is not multiplicative. The first nonmultiplicative term is a(72) = 37 which is not multiplicative since a(8)*a(9) = 5*5 = 25. - _Andrew Howroyd_, Feb 12 2018
%H A038389 Andrew Howroyd, <a href="/A038389/b038389.txt">Table of n, a(n) for n = 1..1000</a>
%t A038389 Table[k = 1; While[Nand @@ IntegerQ /@ {a = (n + k)/2, Sqrt[n*k]}, k++]; a, {n, 78}] (* _Jayanta Basu_, Jul 14 2013 *)
%o A038389 (PARI) a(n)={for(k=1, n, if((n+k)%2==0 && issquare(n*k), return((n+k)/2)))} \\ _Andrew Howroyd_, Feb 12 2018
%Y A038389 Cf. A038387, A038388.
%K A038389 nonn
%O A038389 1,2
%A A038389 _N. J. A. Sloane_

# Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE