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A217976 First time n appears in the first differences of n*log(n): A217865. 1

%I #5 Oct 16 2012 14:26:13

%S 1,2,4,9,21,62,159,422,1134,3056,8139,22169,60004,163262,443002

%N First time n appears in the first differences of n*log(n): A217865.

%C Conjecture: the last time n appears is always before the first time n+2 appears.

%C For example the last time 5 appears is at position 135, the first time 7 appears is at position 159.

%o (JavaScript)

%o function firstIndex(arr,k) {

%o p=-1;

%o for (a=1;a<arr.length;a++) if (arr[a]==k) {p=a;return p;}

%o return p;

%o }

%o d=new Array();

%o for (i=1; i<500000; i++)

%o d[i]=Math.floor((i+1)*Math.log(i+1))-Math.floor(i*Math.log(i));

%o for (i=1; i<100; i++) document.write(firstIndex(d, i)+", ");

%Y Cf. A217866.

%K nonn

%O 1,2

%A _Jon Perry_, Oct 16 2012

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Last modified April 14 13:58 EDT 2024. Contains 371665 sequences. (Running on oeis4.)