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Trajectory of 2 under repeated application of the map n -> n + square excess of n.
3

%I #9 Jan 28 2018 02:42:21

%S 2,3,5,6,8,12,15,21,26,27,29,33,41,46,56,63,77,90,99,117,134,147,150,

%T 156,168,192,215,234,243,261,266,276,296,303,317,345,366,371,381,401,

%U 402,404,408,416,432,464,487,490,496,508,532,535,541,553,577,578,580,584,592,608

%N Trajectory of 2 under repeated application of the map n -> n + square excess of n.

%H Robert Israel, <a href="/A094763/b094763.txt">Table of n, a(n) for n = 0..10000</a>

%H S. H. Weintraub, <a href="http://www.jstor.org/stable/4145074">An interesting recursion</a>, Amer. Math. Monthly, 111 (No. 6, 2004), 528-530.

%p a[0]:= 2:

%p for n from 1 to 100 do a[n]:= f(a[n-1]) od:

%p seq(a[n],n=0..100); # _Robert Israel_, Jan 28 2018

%o (PARI) lista(nn) = {print1(n=2, ", "); for (k=2, nn, m = 2*n - sqrtint(n)^2; print1(m, ", "); n = m;);} \\ _Michel Marcus_, Oct 23 2015

%Y Cf. A053186, A094761, A094764.

%K nonn

%O 0,1

%A _N. J. A. Sloane_, Jun 10 2004