login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A135284 Sum of staircase twin primes according to the rule: top + bottom - next top. 0
3, 1, 7, 7, 19, 25, 49, 43, 97, 79, 127, 121, 169, 187, 169, 217, 211, 259, 253, 277, 277, 409, 403, 403, 475, 541, 583, 595, 625, 511, 799, 817, 799, 835, 745, 1009, 1015, 1039, 1033, 1033, 1075, 1183, 1267, 1279, 1285, 1213, 1405, 1423, 1477, 1369, 1597, 1573 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The case for bottom - top + next top produces A006512(n+1), the upper twin primes > 5.

LINKS

Table of n, a(n) for n=1..52.

FORMULA

We list the twin primes in staircase fashion as in A135283. Then a(n) = tl(n) + tu(n) + (-tl(n+1)).

a(n) = A054735(n)-A001359(n+1). - R. J. Mathar, Sep 10 2016

PROG

(PARI) g(n) = for(x=1, n, y=twinu(x) + twinl(x) - twinl(x+1); print1(y", ")) twinl(n) = / *The n-th lower twin prime. */ { local(c, x); c=0; x=1; while(c<n, if(ispseudoprime(prime(x)+2), c++); x++; ); return(prime(x-1)) } twinu(n) = /* The n-th upper twin prime. */ { local(c, x); c=0; x=1; while(c<n, if(isprime(prime(x)+2), c++); x++; ); return(prime(x)) }

CROSSREFS

Sequence in context: A319298 A101748 A058606 * A016647 A091039 A217594

Adjacent sequences: A135281 A135282 A135283 * A135285 A135286 A135287

KEYWORD

nonn

AUTHOR

Cino Hilliard, Dec 03 2007

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 28 21:48 EST 2022. Contains 358421 sequences. (Running on oeis4.)