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

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A019296 Values of n for which exp(Pi*sqrt(n)) is very close to an integer. 4
-1, 0, 6, 17, 18, 22, 25, 37, 43, 58, 59, 67, 74, 103, 148, 149, 163, 164, 177, 205, 223, 226, 232, 267, 268, 326, 359, 386, 522, 566, 630, 638, 652, 719, 790, 792, 928, 940, 986, 1005, 1014, 1169, 1194, 1213, 1245, 1257, 1293, 1326, 1332, 1353, 1441, 1467 (list; graph; refs; listen; history; text; internal format)
OFFSET

-1,3

COMMENTS

Very close is defined here as being less than 1/100.

e^(Pi*sqrt(163)) is 262537412640768743.9999999999992500725971981856888... and no closer exponent of this character has been discovered. See A069014.

LINKS

Table of n, a(n) for n=-1..50.

MATHEMATICA

Select[ Range[ -1, 1480], Abs[ Round[E^(Pi*Sqrt[ # ])] - E^(Pi*Sqrt[ # ])] < 0.01 &]

PROG

(Contribution from M. F. Hasler, Jan 26 2014) (Start)

/* Adjusting the p-value allows one to select more interesting subsequences. */

(PARI) is_A019296(n, p=2)=abs(frac(exp(sqrt(n)*Pi))-.5)>.5-.1^p

(PARI) {p=.5-.1^2; for(n=1, 9e9, abs(frac(exp(sqrt(n)*Pi))-.5)>p&&print1(round(exp(sqrt(n)*Pi))", ")) \\ (End)

CROSSREFS

Cf. A003173, A019297, A035484, A069014.

Sequence in context: A112366 A095421 A063584 * A035484 A277684 A009171

Adjacent sequences:  A019293 A019294 A019295 * A019297 A019298 A019299

KEYWORD

sign

AUTHOR

Roy Williams Clickery (roy(AT)ccsf.caltech.edu)

EXTENSIONS

Edited and extended by Robert G. Wilson v, Sep 07 2003

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified November 24 07:58 EST 2017. Contains 295173 sequences.