login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A191910 Triangle read by rows: T(n,n)=n; T(n,k) = k-1 if k divides n and k < n, otherwise -1. 2
1, 0, 2, 0, -1, 3, 0, 1, -1, 4, 0, -1, -1, -1, 5, 0, 1, 2, -1, -1, 6, 0, -1, -1, -1, -1, -1, 7, 0, 1, -1, 3, -1, -1, -1, 8, 0, -1, 2, -1, -1, -1, -1, -1, 9, 0, 1, -1, -1, 4, -1, -1, -1, -1, 10, 0, -1, -1, -1, -1, -1, -1, -1, -1, -1, 11, 0, 1, 2, 3, -1, 5, -1, -1, -1, -1, -1, 12, 0, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 13 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

The double limit lim_{k->infinity} (lim_{m->infinity} (Sum_{n=1..m} T(n,k)/n)) equals the Euler-Mascheroni constant A001620.

LINKS

Table of n, a(n) for n=1..91.

EXAMPLE

Triangle starts:

1;

0, 2;

0, -1, 3;

0, 1, -1, 4;

0, -1, -1, -1, 5;

0, 1, 2, -1, -1, 6;

0, -1, -1, -1, -1, -1, 7;

0, 1, -1, 3, -1, -1, -1, 8;

0, -1, 2, -1, -1, -1, -1, -1, 9;

MAPLE

A191910 := proc(n, k) if n = k then n; elif modp(n, k) = 0 then k-1 ; else -1; end if; end proc: seq(seq(A191910(n, k), k=1..n), n=1..20); # R. J. Mathar, Aug 03 2011

MATHEMATICA

Clear[t];

nn = 13;

t[n_, k_] :=

t[n, k] = If[n <= k, 1, 0] - If[Mod[n, k] == 0, (1 - k), 1];

Flatten[Table[Table[t[n, k], {k, 1, n}], {n, 1, nn}]]

(*The double limit for gamma:*)

Clear[t];

nn = 1000;

kk = 60;

t[n_, k_] :=

t[n, k] = If[n <= k, 1, 0] - If[Mod[n, k] == 0, (1 - k), 1];

a = Table[t[n, kk], {n, 1, nn}];

MatrixForm[a];

b = Range[nn];

gamma = N[Total[a/b]]

CROSSREFS

Cf. A001620, A191907.

Sequence in context: A141097 A278045 A096335 * A129503 A225682 A144185

Adjacent sequences: A191907 A191908 A191909 * A191911 A191912 A191913

KEYWORD

sign,tabl,easy

AUTHOR

Mats Granvik, Jun 19 2011

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 6 12:58 EST 2022. Contains 358634 sequences. (Running on oeis4.)