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 1-6 of 6 results.

A278051 Let v = list of denominators of Farey series of order n (see A006843); let b(n) = Sum 1/(k+k'), where (k,k') are pairs of successive terms of v; a(n) = denominator of b(n).

Original entry on oeis.org

2, 3, 10, 35, 252, 2772, 6435, 858, 680680, 12932920, 5290740, 121687020, 1029659400, 3088978200, 582272390700, 18050444111700, 128701918800, 25740383760, 70301729698200, 10043104242600, 109530094869795600, 523310453266801200, 51193413906534900, 481218090721428060
Offset: 1

Views

Author

N. J. A. Sloane, Nov 23 2016

Keywords

Examples

			The fractions b(n) are 1/2, 2/3, 9/10, 38/35, 347/252, 4189/2772, 11767/6435, 1733/858, 1548081/680680, 31464371/12932920, 14680543/5290740, 353517989/121687020, 3350216417/1029659400, 10571768267/3088978200, ...
		

Crossrefs

Programs

  • Maple
    Farey := proc(n) sort(convert(`union`({0}, {seq(seq(m/k, m=1..k), k=1..n)}), list)) end:
    ans:=[];
    for n from 1 to 30 do
    t1:=denom(Farey(n));
    t2:=add( 1/(t1[i]+t1[i+1]), i=1..nops(t1)-1);
    ans:=[op(ans),t2];
    od:
    ans;
    map(numer,ans); # A278050
    map(denom,ans); # A278051

A278047 Let v = list of denominators of Farey series of order n (see A006843); let b(n) = Sum 1/(k*k'*(k+k')), where (k,k') are pairs of successive terms of v; a(n) = numerator of b(n).

Original entry on oeis.org

1, 1, 7, 4, 37, 53, 707, 85, 179077, 289613, 379721, 641671, 62836087, 35819033, 6367281023, 55181728027, 13442946373, 490167893, 596530310479, 576997238399, 116144361532321, 4931206160615, 164890340129357, 1514840590670747, 10181612956306486603, 3295813969039399097
Offset: 1

Views

Author

N. J. A. Sloane, Nov 22 2016

Keywords

Examples

			The fractions b(n) are 1/2, 1/3, 7/30, 4/21, 37/252, 53/396, 707/6435, 85/858, 179077/2042040, 289613/3527160, 379721/5290740, 641671/9360540, 62836087/1029659400, 35819033/617795640, ...
		

Crossrefs

Programs

  • Maple
    Farey := proc(n) sort(convert(`union`({0}, {seq(seq(m/k, m=1..k), k=1..n)}), list)) end:
    ans:=[];
    for n from 1 to 50 do
    t1:=denom(Farey(n));
    t2:=add( 1/(t1[i]*t1[i+1]*(t1[i]+t1[i+1])),i=1..nops(t1)-1);
    ans:=[op(ans),t2];
    od:
    ans;
    map(numer,ans); # A278047
    map(denom,ans); # A278048

A278048 Let v = list of denominators of Farey series of order n (see A006843); let b(n) = Sum 1/(k*k'*(k+k')), where (k,k') are pairs of successive terms of v; a(n) = denominator of b(n).

Original entry on oeis.org

2, 3, 30, 21, 252, 396, 6435, 858, 2042040, 3527160, 5290740, 9360540, 1029659400, 617795640, 116454478140, 1061790830100, 283144221360, 10644519600, 14060345939640, 14060345939640, 2960272834318800, 130015019445168, 4653946718775900, 43747099156493460
Offset: 1

Views

Author

N. J. A. Sloane, Nov 22 2016

Keywords

Examples

			The fractions b(n) are 1/2, 1/3, 7/30, 4/21, 37/252, 53/396, 707/6435, 85/858, 179077/2042040, 289613/3527160, 379721/5290740, 641671/9360540, 62836087/1029659400, 35819033/617795640, ...
		

Crossrefs

Programs

  • Maple
    Farey := proc(n) sort(convert(`union`({0}, {seq(seq(m/k, m=1..k), k=1..n)}), list)) end:
    ans:=[];
    for n from 1 to 50 do
    t1:=denom(Farey(n));
    t2:=add( 1/(t1[i]*t1[i+1]*(t1[i]+t1[i+1])),i=1..nops(t1)-1);
    ans:=[op(ans),t2];
    od:
    ans;
    map(numer,ans); # A278047
    map(denom,ans); # A278048

A278050 Let v = list of denominators of Farey series of order n (see A006843); let b(n) = Sum 1/(k+k'), where (k,k') are pairs of successive terms of v; a(n) = numerator of b(n).

Original entry on oeis.org

1, 2, 9, 38, 347, 4189, 11767, 1733, 1548081, 31464371, 14680543, 353517989, 3350216417, 10571768267, 2114915577977, 69039991480573, 538250871701, 110983833313, 328448743696081, 48484885139543, 553270527392631611, 2736415713954900433, 286367762285513933, 2754025786313797907
Offset: 1

Views

Author

N. J. A. Sloane, Nov 23 2016

Keywords

Examples

			The fractions b(n) are 1/2, 2/3, 9/10, 38/35, 347/252, 4189/2772, 11767/6435, 1733/858, 1548081/680680, 31464371/12932920, 14680543/5290740, 353517989/121687020, 3350216417/1029659400, 10571768267/3088978200, ...
		

Crossrefs

Programs

  • Maple
    Farey := proc(n) sort(convert(`union`({0}, {seq(seq(m/k, m=1..k), k=1..n)}), list)) end:
    ans:=[];
    for n from 1 to 30 do
    t1:=denom(Farey(n));
    t2:=add( 1/(t1[i]+t1[i+1]), i=1..nops(t1)-1);
    ans:=[op(ans),t2];
    od:
    ans;
    map(numer,ans); # A278050
    map(denom,ans); # A278051

A278052 Let v = list of denominators of Farey series of order n (see A006843); let b(n) = Sum k*k'/(k+k'), where (k,k') are pairs of successive terms of v; a(n) = numerator of b(n).

Original entry on oeis.org

1, 4, 39, 52, 4069, 8573, 258017, 46639, 53371999, 113518551, 768140741, 1560819091, 242830653007, 169134016817, 38186305937387, 408881289764107, 143220706672837, 41293923006131, 9928250098118791, 10936700271572951, 97615258031147892517, 643700119549549507, 62211198375587838727
Offset: 1

Views

Author

N. J. A. Sloane, Nov 23 2016

Keywords

Examples

			The fractions b(n) are 1/2, 4/3, 39/10, 52/7, 4069/252, 8573/396, 258017/6435, 46639/858, 53371999/680680, 113518551/1175720, 768140741/5290740, 1560819091/9360540, 242830653007/1029659400, 169134016817/617795640, 38186305937387/116454478140, ...
		

Crossrefs

Cf. A006843, A005728, A240877, A278046-A278051, A278561 (denominators).

Programs

  • Maple
    Farey := proc(n) sort(convert(`union`({0}, {seq(seq(m/k, m=1..k), k=1..n)}), list)) end:
    ans:=[];
    for n from 1 to 30 do
    t1:=denom(Farey(n));
    t2:=add( t1[i]*t1[i+1]/(t1[i]+t1[i+1]), i=1..nops(t1)-1);
    od:
    ans;
    map(numer,ans); # A278052
    map(denom,ans); # A278561

A278561 Let v = list of denominators of Farey series of order n (see A006843); let b(n) = Sum k*k'/(k+k'), where (k,k') are pairs of successive terms of v; a(n) = denominator of b(n).

Original entry on oeis.org

2, 3, 10, 7, 252, 396, 6435, 858, 680680, 1175720, 5290740, 9360540, 1029659400, 617795640, 116454478140, 1061790830100, 283144221360, 74511637200, 14060345939640, 14060345939640, 109530094869795600, 650075097225840, 51193413906534900, 481218090721428060
Offset: 1

Views

Author

N. J. A. Sloane, Nov 23 2016

Keywords

Examples

			The fractions b(n) are 1/2, 4/3, 39/10, 52/7, 4069/252, 8573/396, 258017/6435, 46639/858, 53371999/680680, 113518551/1175720, 768140741/5290740, 1560819091/9360540, 242830653007/1029659400, 169134016817/617795640, 38186305937387/116454478140, ...
		

Crossrefs

Programs

  • Maple
    Farey := proc(n) sort(convert(`union`({0}, {seq(seq(m/k, m=1..k), k=1..n)}), list)) end:
    ans:=[];
    for n from 1 to 30 do
    t1:=denom(Farey(n));
    t2:=add( t1[i]*t1[i+1]/(t1[i]+t1[i+1]), i=1..nops(t1)-1);
    od:
    ans;
    map(numer,ans); # A278052
    map(denom,ans); # A278561
Showing 1-6 of 6 results.