

A135286


Sum of staircase twin primes according to the rule: top * bottom + next top.


0



20, 46, 160, 352, 940, 1822, 3670, 5284, 10510, 11800, 19192, 22678, 32590, 37060, 39430, 52222, 57868, 73180, 79834, 97690, 121522, 176830, 187084, 213964, 273052, 325498, 360616, 382564, 412822, 436408, 656920, 676510, 686440, 737044, 778942, 1041430, 1066072, 1103560, 1128934, 1193614, 1328332, 1514176, 1634572, 1665400, 1696522, 1743826, 2040634, 2109784, 2197810, 2215750
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OFFSET

1,1


COMMENTS

While there is multiplication in the generation of this sequence, it is still called a sum because the arithmetic processes ,*,/ are derived from addition.


LINKS

Table of n, a(n) for n=1..50.


FORMULA

We list the twin primes in staircase fashion as in A135283. Then a(n) = tl(n) * tu(n) + tl(n+1).
a(n) = A037074(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 nth lower twin prime. */ { local(c, x); c=0; x=1; while(c<n, if(ispseudoprime(prime(x)+2), c++); x++; ); return(prime(x1)) } twinu(n) = /* The nth 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: A145220 A234266 A234259 * A338235 A177725 A264444
Adjacent sequences: A135283 A135284 A135285 * A135287 A135288 A135289


KEYWORD

nonn


AUTHOR

Cino Hilliard, Dec 03 2007


EXTENSIONS

All the entries were wrong. They have been corrected by Franklin T. AdamsWatters, Apr 29 2008


STATUS

approved



