cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-10 of 14 results. Next

A127029 Let f(n) = exp(Pi*sqrt(n)); sequence gives numbers n such that f(n) - floor(f(n)) < 1/10^4.

Original entry on oeis.org

652, 2608, 5868, 14370, 22905, 23325, 28201, 34218, 45374, 54295, 55003, 59266, 66499, 76750, 87228, 91311, 95041, 160874, 169259, 184867, 192157, 196681, 197869, 206495, 206656, 210532, 210676, 230491, 251572, 273117, 289732, 301417, 311669, 317780, 321484
Offset: 1

Views

Author

Artur Jasinski, Jan 03 2007

Keywords

Crossrefs

Programs

  • Mathematica
    $MaxExtraPrecision = 1000; a = {}; Do[If[((Exp[Pi Sqrt[x]] - Floor[Exp[Pi Sqrt[x]]]) > 0) && ((Exp[Pi Sqrt[x]] - Floor[Exp[Pi Sqrt[x]]]) < 10^(-4)), AppendTo[a, x]], {x, 1, 20000}]; a

Extensions

a(5)-a(35) from Jon E. Schoenfield, Sep 04 2017

A127022 Let f(k) = exp(Pi*sqrt(k)); sequence gives numbers k such that ceiling(f(k)) - f(k) < 1/10^3.

Original entry on oeis.org

25, 37, 43, 58, 67, 74, 163, 232, 522, 719, 1169, 1245, 1467, 1850, 1872, 2086, 3368, 4075, 5773, 7685, 7802, 7942, 8325, 9728, 10032, 11682, 12158, 13574, 17908, 18505, 19183, 19396, 20039, 20244, 20584, 22241, 23773, 23778, 23834, 25004, 27573, 28071, 32497
Offset: 1

Views

Author

Artur Jasinski, Jan 03 2007

Keywords

Crossrefs

Programs

  • Magma
    SetDefaultRealField(RealField(500)); R:= RealField(); [n: n in [1..50000] | Ceiling(Exp(Pi(R)*Sqrt(n))) - Exp(Pi(R)*Sqrt(n)) lt 1/1000]; // G. C. Greubel, Jun 02 2019
  • Mathematica
    a = {}; Do[If[(1 - (Exp[Pi Sqrt[x]] - Floor[Exp[Pi Sqrt[x]]]) > 0) && (1 - ( Exp[Pi Sqrt[x]] - Floor[Exp[Pi Sqrt[x]]])< 10^(-3)), AppendTo[a, x]], {x, 1, 1000}]; a
    Reap[Block[{$MaxExtraPrecision = Infinity}, Do[If[N[FractionalPart[Exp[Pi Sqrt[n]]], 8] > .999, Sow[n]], {n, 2000}]]][[-1, 1]] (* JungHwan Min, Mar 20 2016 *)
  • PARI
    default(realprecision, 500); c(n) = exp(Pi*sqrt(n));
    for(n=1, 50000, if( ceil(c(n)) - c(n) <1/1000, print1(n", "))) \\ G. C. Greubel, Jun 02 2019
    

Extensions

a(16)-a(43) added (from JungHwan Min's b-file) by Jon E. Schoenfield, Sep 04 2017

A127024 Let f(n) = exp(Pi*sqrt(n)); sequence gives numbers n such that ceiling(f(n)) - f(n) < 1/10^5.

Original entry on oeis.org

58, 67, 163, 232, 1467, 4075, 343732, 357711, 478233, 486396, 881967, 1003957, 1033466, 1045512, 1053883, 1091706, 1208198, 1240173, 1341615, 1844122, 1878006, 1964724, 2177184, 2259143, 2276046, 2279335, 2488542, 2691364, 2850458, 3157407, 3262163, 3310971
Offset: 1

Views

Author

Artur Jasinski, Jan 03 2007

Keywords

References

  • J.-P. Serre, "Lectures on the Mordell-Weil theorem".

Crossrefs

Programs

  • Mathematica
    a = {}; Do[If[(1 - (Exp[Pi Sqrt[x]] - Floor[Exp[Pi Sqrt[x]]]) > 0) && (1 - ( Exp[Pi Sqrt[x]] - Floor[Exp[Pi Sqrt[x]]])< 10^(-5)), AppendTo[a, x]], {x, 1, 1000}]; a

Extensions

a(6)-a(32) from Jon E. Schoenfield, Sep 04 2017

A127025 Let f(n) = exp(Pi*sqrt(n)); sequence gives numbers n such that ceiling(f(n)) - f(n) < 1/10^6.

Original entry on oeis.org

58, 163, 1467, 478233, 881967, 1053883, 1341615, 1844122, 3498092, 6069493, 6396611, 8707530, 10414308, 13340780, 16039620, 17013933, 17226343, 18577932, 19390220, 21991290, 24529596, 26202225, 26634713, 26651262, 26848308, 27497372, 32149837, 35437319, 35892748
Offset: 1

Views

Author

Artur Jasinski, Jan 03 2007

Keywords

Crossrefs

Programs

  • Mathematica
    a = {}; Do[If[(1 - (Exp[Pi Sqrt[x]] - Floor[Exp[Pi Sqrt[x]]]) > 0) && (1 - ( Exp[Pi Sqrt[x]] - Floor[Exp[Pi Sqrt[x]]])< 10^(-6)), AppendTo[a, x]], {x, 1, 1000}]; a
  • PARI
    is(n)=my(t);default(realprecision, 40);default(realprecision, Pi*sqrt(n)\log(10)+40); t=exp(Pi*sqrt(n));ceil(t)-t<1e-6 \\ Charles R Greathouse IV, Feb 20 2012

Extensions

a(4)-a(20) from Charles R Greathouse IV, Feb 20 2012
a(21)-a(36) from Charles R Greathouse IV, Feb 23 2012

A127023 Let f(n) = exp(Pi*sqrt(n)); sequence gives numbers n such that ceiling(f(n)) - f(n) < 1/10^4.

Original entry on oeis.org

37, 58, 67, 163, 232, 719, 1169, 1467, 4075, 5773, 19183, 33563, 65477, 67893, 68996, 70273, 81194, 90857, 106194, 112070, 117434, 120332, 122456, 133074, 167196, 210500, 226081, 254883, 261084, 263987, 270154, 281128, 298455, 301487, 313447, 321349, 325779
Offset: 1

Views

Author

Artur Jasinski, Jan 03 2007

Keywords

Crossrefs

Programs

  • Mathematica
    a = {}; Do[If[(1 - (Exp[Pi Sqrt[x]] - Floor[Exp[Pi Sqrt[x]]]) > 0) && (1 - ( Exp[Pi Sqrt[x]] - Floor[Exp[Pi Sqrt[x]]])< 10^(-4)), AppendTo[a, x]], {x, 1, 1000}]; a

Extensions

a(9)-a(37) from Jon E. Schoenfield, Sep 04 2017

A127031 Let f(n) = exp(Pi*sqrt(n)); sequence gives numbers n such that f(n) - floor(f(n)) < 1/10^6.

Original entry on oeis.org

652, 2608, 880111, 2720885, 4089051, 4619054, 5046630, 5409046, 5433402, 5603556, 5645558, 7278138, 7466589, 10037029, 10730786, 10823358, 11540978, 11860073, 12898258, 14554227, 15107659, 15602035, 15896143, 17070573, 18204473, 19252185, 19425342, 19556500
Offset: 1

Views

Author

Artur Jasinski, Jan 03 2007

Keywords

Comments

a(212)=195246501 is the smallest integer such that the fractional part of e^(Pi*sqrt(n)) begins with exactly 8 zeros. - Anthony Canu, Oct 11 2017

Examples

			5 is not in the sequence since exp(Pi*sqrt(5)) = 1124.186... has fractional part 0.186... which is greater than 1/10^6. But exp(Pi*sqrt(652)) has fractional part 0.0000000001637... which is less than 1/10^6, so 652 is in the sequence. - _Michael B. Porter_, Aug 24 2016
		

Crossrefs

Programs

  • Mathematica
    $MaxExtraPrecision = 1000; a = {}; Do[If[((Exp[Pi Sqrt[x]] - Floor[Exp[Pi Sqrt[x]]]) > 0) && ((Exp[Pi Sqrt[x]] - Floor[Exp[Pi Sqrt[x]]]) < 10^(-6)), AppendTo[a, x]], {x, 1, 100000}]; a
  • PARI
    search(a,b)=my(t,prec=default(realprecision), nprec=round(Pi*sqrt(b)/log(10)+20)); default(realprecision,nprec); for(n=floor(a),b,t=exp(Pi*sqrt(n));if(t-floor(t)<.000001, print(n))); default(realprecision,prec) \\ Charles R Greathouse IV, Jul 28 2009

Extensions

a(3)-a(14) from Charles R Greathouse IV, Jul 28 2009
a(15)-a(18) from Anthony Canu, Aug 24 2016
a(19) from Anthony Canu, Aug 31 2016
a(20)-a(28) from Anthony Canu, Mar 03 2017

A056581 Nearest integer to 1/(A056580(n) - exp(sqrt(n)*Pi)).

Original entry on oeis.org

-7, -51, 4, -2, -5, 110, 15, -3, 3, 5, -7, -3, 19, 4, 5, -3, 430, 141, 4, 4, -2, 574, 3, 7, 1518, -3, 62, 84, -2, -10, 11, -7, -13, -4, 4, -3, 45551, -5, 3, 3, 2, -33, 4494, -8, -5, -6, 3, -2, 7, 2, 9, -3, -4, -4, 3, -17, -2, 5624716, 147, -5, 4, 3, 3, 2, 6, -2, 747638
Offset: 1

Views

Author

Henry Bottomley, Jun 30 2000

Keywords

Comments

A measure of how close e^(Pi*sqrt(n)) is to an integer (higher absolute value of a(n) means closer, negative value means the closest integer is smaller than it).
The sign convention is chosen so that most terms and in particular record values such as those occurring for the Heegner numbers A003173, are positive, so that A069014 lists record indices of this sequence (except for A069014(2)=2 instead of 3 for signed values). The sequence is not defined for n=0,-1 where e^(sqrt(n)*Pi) is an integer. - M. F. Hasler, Apr 15 2008
Negative resp. positive values of a(n) correspond to 2nd resp. 3rd term of the continued fraction expansion of exp(sqrt(n)*Pi), up to a difference of -1 or -2 depending on the direction of rounding. - M. F. Hasler, Apr 15 2008

Examples

			a(6)=110, since e^(Pi*sqrt(6)) = 2197.9908695... and 1/(2198-2197.9908695...) = 109.52... which rounds to 110.
e^(Pi*sqrt(163)) = 262537412640768743.9999999999992500725971981... (the Ramanujan number) and so a(163)=1333462407513.
		

References

  • For links, references and more information see A019296 and other cross-referenced sequences.

Crossrefs

Programs

  • PARI
    default(realprecision,100); dZ(x)=round(x)-x
    A056581(n)=round(1/dZ(exp(sqrt(n)*Pi)))

Formula

a(n) = 1/(A056580(n) - e^(sqrt(n)*Pi)).
A019296 ={-1, 0} U { n | abs(A056581(n)) > 100} U { some n for which abs(A056581(n)) = 100 }. - M. F. Hasler, Apr 15 2008

Extensions

Definition, formulas and values corrected and extended by M. F. Hasler, Apr 15 2008

A127026 Let f(n) = exp(Pi*sqrt(n)); sequence gives numbers n such that f(n)-floor(f(n)) < 1/10.

Original entry on oeis.org

2, 30, 33, 42, 56, 96, 100, 103, 140, 148, 164, 171, 172, 182, 187, 188, 205, 211, 223, 226, 239, 241, 243, 253, 268, 300, 318, 328, 359, 361, 364, 379, 387, 394, 408, 410, 421, 423, 425, 426, 436, 455, 465, 467, 490, 492, 509, 529, 536, 546, 579, 583, 587
Offset: 1

Views

Author

Artur Jasinski, Jan 03 2007

Keywords

Crossrefs

Programs

  • Mathematica
    a = {}; Do[If[((Exp[Pi Sqrt[x]] - Floor[Exp[Pi Sqrt[x]]]) > 0) && (( Exp[Pi Sqrt[x]] - Floor[Exp[Pi Sqrt[x]]])< 10^(-1)), AppendTo[a, x]], {x, 1, 1000}]; a

A127027 Let f(n) = exp(Pi*sqrt(n)); sequence gives numbers n such that f(n) - floor(f(n)) < 1/10^2.

Original entry on oeis.org

103, 148, 164, 205, 223, 226, 268, 359, 630, 652, 940, 1005, 1194, 1213, 1332, 1353, 1441, 1481, 1519, 1750, 1823, 1825, 1835, 1930, 1951, 1961, 2309, 2339, 2347, 2357, 2498, 2511, 2527, 2554, 2608, 2683, 3086, 3108, 3157, 3377, 3646, 3653, 3656, 3738, 3762
Offset: 1

Views

Author

Artur Jasinski, Jan 03 2007

Keywords

Crossrefs

Programs

  • Mathematica
    a = {}; Do[If[((Exp[Pi Sqrt[x]] - Floor[Exp[Pi Sqrt[x]]]) > 0) && (( Exp[Pi Sqrt[x]] - Floor[Exp[Pi Sqrt[x]]])< 10^(-2)), AppendTo[a, x]], {x, 1, 1000}]; a
    epsQ[n_]:=Module[{c=Exp[Pi*Sqrt[n]],min=1/10^2},0Harvey P. Dale, Apr 06 2012 *)

Extensions

Corrected by Harvey P. Dale, Apr 06 2012
a(27)-a(45) from Jon E. Schoenfield, Sep 04 2017

A127028 Let f(n) = exp(Pi*sqrt(n)); sequence gives numbers n such that f(n) - floor(f(n)) < 1/10^3.

Original entry on oeis.org

148, 268, 652, 1194, 1332, 1519, 2608, 5650, 5774, 5868, 6632, 7260, 9058, 10153, 10210, 11076, 12314, 13049, 13097, 14370, 15696, 16170, 18736, 19571, 21655, 21814, 22905, 23325, 24496, 27435, 28201, 29239, 31214, 34218, 36166, 36287, 38805, 38990, 42761
Offset: 1

Views

Author

Artur Jasinski, Jan 03 2007

Keywords

Crossrefs

Programs

  • Mathematica
    a = {}; Do[If[((Exp[Pi Sqrt[x]] - Floor[Exp[Pi Sqrt[x]]]) > 0) && (( Exp[Pi Sqrt[x]] - Floor[Exp[Pi Sqrt[x]]])< 10^(-3)), AppendTo[a, x]], {x, 1, 1000}]; a

Extensions

a(7)-a(39) from Jon E. Schoenfield, Sep 04 2017
Showing 1-10 of 14 results. Next