login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A217976 First time n appears in the first differences of n*log(n): A217865. 1
1, 2, 4, 9, 21, 62, 159, 422, 1134, 3056, 8139, 22169, 60004, 163262, 443002 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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

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

LINKS

Table of n, a(n) for n=1..15.

PROG

(JavaScript)

function firstIndex(arr, k) {

p=-1;

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

return p;

}

d=new Array();

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

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

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

CROSSREFS

Cf. A217866.

Sequence in context: A148075 A058718 A148076 * A156801 A057580 A129875

Adjacent sequences:  A217973 A217974 A217975 * A217977 A217978 A217979

KEYWORD

nonn

AUTHOR

Jon Perry, Oct 16 2012

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 17 12:32 EST 2020. Contains 331996 sequences. (Running on oeis4.)