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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: A188463 A101748 A058606 * A016647 A091039 A217594

Adjacent sequences:  A135281 A135282 A135283 * A135285 A135286 A135287

KEYWORD

nonn

AUTHOR

Cino Hilliard, Dec 03 2007

STATUS

approved

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Last modified March 28 21:25 EDT 2017. Contains 284246 sequences.