login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A125716 Numbers n such that A120292(n) = 1. 4
2, 3, 5, 7, 8, 9, 14, 15, 16, 17, 23, 31, 34, 35, 39, 41, 43, 50, 51, 56, 66, 67, 70, 71, 75, 77, 92, 96, 97, 98, 101, 107, 112, 115, 117, 123, 131, 132, 153, 155, 156, 160, 163, 165, 166, 170, 172, 182, 185, 196, 198, 200, 203, 204, 207, 212, 218, 231, 243, 246, 249 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A120292(n) = {2, 1, 1, 5, 1, 23, 1, 1, 1, 23, 17, 13, 5, 1, 1, 1, 1, 37, ...} Absolute value of numerator of determinant of n X n matrix with elements M[i,j] = Prime[i]/(1+Prime[i]) if i=j and 1 otherwise.

LINKS

Table of n, a(n) for n=1..61.

MATHEMATICA

Do[f=Abs[Numerator[Det[DiagonalMatrix[Table[Prime[i]/(Prime[i]+1)-1, {i, 1, n}]]+1]]]; If[ f == 1, Print[n]], {n, 1, 256}]

CROSSREFS

Cf. A120292.

Sequence in context: A091532 A108345 A073629 * A171614 A029601 A290985

Adjacent sequences:  A125713 A125714 A125715 * A125717 A125718 A125719

KEYWORD

hard,nonn

AUTHOR

Alexander Adamchuk, Feb 02 2007

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 20 22:51 EST 2019. Contains 320362 sequences. (Running on oeis4.)