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a(n) = nearest integer to k*sin(sqrt(k)+j*Pi) where n = 2*k+j, j=0 or 1.
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%I #19 Jun 20 2016 19:34:16

%S 0,0,1,-1,2,-2,3,-3,4,-4,4,-4,4,-4,3,-3,2,-2,1,-1,0,0,-2,2,-4,4,-6,6,

%T -8,8,-10,10,-12,12,-14,14,-16,16,-18,18,-19,19,-21,21,-22,22,-23,23,

%U -24,24,-24,24,-24,24,-24,24,-23,23,-23,23,-22,22,-20,20,-19,19,-17,17,-15,15,-13,13,-10,10,-7

%N a(n) = nearest integer to k*sin(sqrt(k)+j*Pi) where n = 2*k+j, j=0 or 1.

%H N. J. A. Sloane, <a href="/A274102/b274102.txt">Table of n, a(n) for n = 0..10000</a>

%F a(2n) = A274095(n), a(2n+1) = -A274095(n). - _Chai Wah Wu_, Jun 11 2016

%p Digits:=50:

%p ft:=proc(n,t) local k,j;

%p j:=(n mod t); k:=(n-j)/t;

%p round(evalf(k*sin(sqrt(k)+j*Pi)));

%p end;

%p [seq(ft(n,2),n=0..120)];

%Y Sequences of the same type: A272695, A274086, A274087, A274088, A274090, A274091, A274092, A274095, A274096, A274097, A274101, A274102.

%K sign

%O 0,5

%A _N. J. A. Sloane_, Jun 11 2016

%E Definition corrected by _N. J. A. Sloane_, Jun 20 2016