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.

A356793 Decimal expansion of sum of squares of reciprocals of lesser twin primes, Sum_{j>=1} 1/(A001359(j))^2.

Original entry on oeis.org

1, 6, 5, 6, 1, 8, 4, 6, 5, 3, 9, 5
Offset: 0

Views

Author

Artur Jasinski, Sep 04 2022

Keywords

Comments

Alternative definition: sum of squares of reciprocals of primes whose distance from the next prime is equal to 2.
Convergence table:
k A001359(k) Sum_{j=1..k} 1/A001359(j)^2
10000000 3285916169 0.165618465394273171950874120818
20000000 7065898967 0.165618465394707600197099741096
30000000 11044807451 0.165618465394836120901019351544
40000000 15151463321 0.165618465394895965582366015390
50000000 19358093939 0.165618465394930089884704869090
60000000 23644223231 0.165618465394951950670948192842
Using the Hardy-Littlewood prediction of the density of twin primes (see A347278), the contribution to the sum after the last entry in the table above can be estimated as 9.056*10^(-14), making the infinite sum ~= 0.16561846539504... . - Hugo Pfoertner, Sep 28 2022

Examples

			0.165618465395...
		

Crossrefs

Extensions

Data extended to ...3, 9, 5 by Hugo Pfoertner, Sep 28 2022

A195099 Inverse permutation of A195098; every positive integer occurs exactly once.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 14, 16, 17, 18, 20, 21, 19, 22, 23, 24, 26, 27, 28, 25, 29, 30, 31, 33, 34, 35, 36, 32, 37, 38, 39, 41, 42, 43, 45, 44, 40, 46, 47, 48, 50, 51, 52, 54, 55, 53, 49, 56, 57, 58, 60, 61, 62, 64, 65, 66, 63, 59, 67, 68, 69
Offset: 1

Views

Author

Clark Kimberling, Sep 08 2011

Keywords

Crossrefs

Programs

A213007 Decimal expansion of Brun's quadruple primes constant.

Original entry on oeis.org

8, 7, 0, 5, 8, 8, 3, 8
Offset: 0

Views

Author

Stanislav Sykora, Jun 01 2012

Keywords

Comments

Infinite sum of the reciprocals of p, p+2, p+6, and p+8, where p ranges over all elements of A007530.
The 9th digit is probably 0.

Examples

			0.8705883800[+-5]
		

References

  • Steven R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, 2003, Section 2.14, p. 133.

Crossrefs

Formula

Sum_{n >= 1} (1/c(n) + 1/(c(n)+2) + 1/(c(n)+6) + 1/(c(n)+8)), where c(n) = A007530(n).

A357059 Decimal expansion of sum of squares of reciprocals of primes whose distance to the next prime is equal to 4, Sum_{j>=1} 1/A029710(j)^2.

Original entry on oeis.org

0, 3, 1, 3, 2, 1, 6, 2, 0, 6, 4, 6
Offset: 0

Views

Author

Artur Jasinski, Sep 10 2022

Keywords

Comments

Convergence table:
k A029710(k) Sum_{j=1..k} 1/A029710(j)^2
10000000 3285441223 0.031321620645456519799598611681
20000000 7067090263 0.031321620645890982910821292996
30000000 11044597393 0.031321620646019474620358985896
40000000 15153534937 0.031321620646079307404248696076
50000000 19360462153 0.031321620646113421819579063642
60000000 23647877233 0.031321620646135276227114122713
70000000 28000392817 0.031321620646150384406674037099

Examples

			0.031321620646...
		

Crossrefs

Programs

  • Mathematica
    aa = {}; Do[g1[2 n] = 0, {n, 1, 1000}]; Do[g2[2 n] = 0, {n, 1, 1000}]; Do[g3[2 n] = 0, {n, 1, 1000}]; Do[g4[2 n] = 0, {n, 1, 1000}]; Do[g[2 n] = 0, {n, 1, 1000}];
    w1 = 3; n = 3; Monitor[While[n < 10^10, w2 = NextPrime[w1]; kk = w2 - w1;
      If[kk < 2000, g[kk] = g[kk] + 1; g1[kk] = g1[kk] + N[1/w1, 1000];g2[kk] = g2[kk] + N[1/w1^2, 1000];g3[kk] = g3[kk] + N[1/w1^3, 1000];g4[kk] = g4[kk] + N[1/w1^4, 1000];
    If[IntegerQ[g[kk]/1000000], Print[{n, w1, kk, g[kk]}];If[kk == 4,AppendTo[aa, {n, w1, kk, g[kk], g1[kk], g2[kk], g3[kk], g4[kk]}]]]];w1 = w2; n++], n];aa

A277774 Decimal expansion of the prime triples constant, also known as Brun's constant B_{3a} = Sum (1/p + 1/(p+2) + 1/(p+6)) as p runs through the initial members of prime triples A022004.

Original entry on oeis.org

1, 0, 9, 7, 8, 5, 1, 0, 3, 9, 6, 7, 9
Offset: 1

Views

Author

Martin Renner, Oct 29 2016

Keywords

Examples

			1.097851039679...
		

References

  • Steven R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, 2003, Section 2.14, p. 133.

Crossrefs

Extensions

Offset corrected by Rick L. Shepherd, Nov 03 2016

A277775 Decimal expansion of the prime triples constant, also known as Brun's constant B_{3b} = Sum (1/p + 1/(p+4) + 1/(p+6)) as p runs through the initial members of prime triples A022005.

Original entry on oeis.org

8, 3, 7, 1, 1, 3, 2, 1, 2, 4, 1, 1
Offset: 0

Views

Author

Martin Renner, Oct 29 2016

Keywords

Examples

			0.837113212411...
		

References

  • Steven R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, 2003, Section 2.14, p. 133.

Crossrefs

Extensions

Offset corrected by Rick L. Shepherd, Nov 03 2016
Showing 1-6 of 6 results.