login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A071990 Numerators of the partial sums of the reciprocals of the upper members of twin prime pairs. 0
1, 12, 191, 4084, 135249, 6083702, 382629607, 28634912196, 3000711370793, 332363027120752, 46774578929554863, 7143041842570860878, 1304982717560745380233, 254050342563254798982984 (list; graph; refs; listen; history; text; internal format)
OFFSET

5,2

COMMENTS

The sum of the reciprocals of the upper bound twin primes is convergent. Proof: If S2 = 1/5 + 1/7 + 1/13 + 1/19 . . . is divergent then S2 + (S1 = 1/3 + 1/5 + 1/11 + 1/17 . . .) is divergent. But S1+S2 = 1/3+1/5 + 1/5+1/7 + 1/11+1/13 ... was proved to be convergent by V. Brun in 1919. So S2 is not divergent and since it is not oscillating, it is convergent as stated.

LINKS

Table of n, a(n) for n=5..18.

EXAMPLE

1/5+1/7+1/13+1/19 = 4084/8645 and 4084 is the fourth entry in the table.

PROG

(PARI) \Sum of the reciprocals of lower bound of twin primes { p=1; for(y=1, n, z=sum(x=1, y, 1/(twin[x]+2)^p); print1(numerator(z)", ") ); print(); print(z+.0); } \Build a twin prime table of lower bounds. Run only once in a session savetwins(n) = { twin = vector(n); c=1; forprime(x=3, n*10, if(isprime(x+2), twin[c]=x; c++; ) ) }

CROSSREFS

Sequence in context: A239294 A294409 A239776 * A230757 A196483 A196716

Adjacent sequences:  A071987 A071988 A071989 * A071991 A071992 A071993

KEYWORD

easy,nonn

AUTHOR

Cino Hilliard, Jan 23 2004

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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 28 03:16 EDT 2021. Contains 347698 sequences. (Running on oeis4.)