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

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A081650 Least nonsquare congruent to i^2 (mod k^2) for all 0<k<=n, i being any integer. 0
2, 5, 13, 73, 409, 801, 1584, 2241, 30601, 30601, 78409, 156825, 862416, 862416, 7929009 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

REFERENCES

Mark A. Herkommer, Number Theory, A Programmer's Guide, McGraw-Hill, New York, 1999, page 315.

EXAMPLE

a(3) = 13 because for (mod 1) (A000037) is the set of all nonsquares, for (mod 4) (A079896) is the set beginning {5, 8, 12, 13, 17, 20, 21, 24, 28, 29, ...} and for (mod 9) (A081642) is the set beginning {10, 13, 18, 19, 22, 27, 28, 31, 37, 40, ...}. The first element of the intersection of these three sets is 13.

PROG

(PARI) t=2:for(n=1, 50, for(m=t, 10^9, if(!issquare(m), f=0:for(k=1, n, if(!issquare((m%(k^2))), f=1:break)): if(!f, print1(m", "):t=m:break))))

CROSSREFS

Cf. A000037, A079896, A081642, A081643, A081644, A081645, A081646, A081647, A081648, A081649.

Sequence in context: A028856 A013497 A128029 * A092262 A032015 A075736

Adjacent sequences:  A081647 A081648 A081649 * A081651 A081652 A081653

KEYWORD

nonn

AUTHOR

Robert G. Wilson v (rgwv(AT)rgwv.com), Mar 26 2003

EXTENSIONS

Edited by Ralf Stephan (ralf(AT)ark.in-berlin.de), Mar 27 2003

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
Recent Additions | More pages | Superseeker | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified February 16 21:51 EST 2012. Contains 205978 sequences.