A137781 a(n) = (2^prime(n) + 2^prime(n+1)) / 4.
3, 10, 40, 544, 2560, 34816, 163840, 2228224, 136314880, 671088640, 34896609280, 584115552256, 2748779069440, 37383395344384, 2286984185774080, 146366987889541120, 720575940379279360, 37469948899722526720, 627189298506124754944
Offset: 1
Links
- G. C. Greubel, Table of n, a(n) for n = 1..460
Programs
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Magma
[(2^NthPrime(n) + 2^NthPrime(n+1)) / 4: n in [1..20]]; // Vincenzo Librandi, Mar 28 2015
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Maple
A137781:=n->(2^ithprime(n)+2^ithprime(n+1))/4: seq(A137781(n), n=1..20); # Wesley Ivan Hurt, Mar 27 2015
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Mathematica
Table[(2^Prime[n] + 2^Prime[n + 1])/4, {n, 20}] (* Wesley Ivan Hurt, Mar 27 2015 *) (2^#[[1]]+2^#[[2]])/4&/@Partition[Prime[Range[20]],2,1] (* Harvey P. Dale, Dec 21 2019 *) -
PARI
vector(15,n,(2^prime(n)+2^prime(n+1))/4) \\ Derek Orr, Mar 29 2015
Formula
From Wesley Ivan Hurt, Mar 27 2015: (Start)
a(n) = A137389(n)/4.
Comments