

A144043


a(2n1) = 2*prime(n), a(2n) = prime(n) + prime(n+1).


1



4, 5, 6, 8, 10, 12, 14, 18, 22, 24, 26, 30, 34, 36, 38, 42, 46, 52, 58, 60, 62, 68, 74, 78, 82, 84, 86, 90, 94, 100, 106, 112, 118, 120, 122, 128, 134, 138, 142, 144, 146, 152, 158, 162, 166, 172, 178, 186, 194, 198, 202, 204
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OFFSET

1,1


COMMENTS

Previous name was "Sum of the middle pair in the nterm sequence 2, 3, 5, ..., prime(n)."  Jon E. Schoenfield, Oct 12 2015
The bisections are the doubled primes (A100484) and the sums of adjacent primes (A001043).  R. J. Mathar, Sep 11 2011


LINKS

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


FORMULA

a(2n1) = 2 prime(n), a(2n) = prime(n) + prime(n+1), n = 1,2,...  Zak Seidov, Jan 15 2014
a(n) = 2*A063934(n1) for n>2.  Michel Marcus, Oct 13 2015


EXAMPLE

4 = sumtwice(2); 5 = sum(2,3); 6 = 2, sumtwice(3), 5, 7; 8 = 2, sum(3,5), 7, 11;


MAPLE

A144043 := proc(n) ithprime(ceil((n+1)/2))+ithprime(ceil(n/2)) ; end proc: # R. J. Mathar, Sep 11 2011


PROG

(MATLAB) clc clear all aP= [primes(1000)]; qN= numel(aP); kL=[]; %init empty result for nn= 1:qN %Loop to sum the central pairs auxT= ceil((nn+1)/2); auxL= ceil(nn/2); kL= [kL; aP(auxL)+aP(auxT)]; end kL %kL is the result


CROSSREFS

Sequence in context: A295485 A226746 A206416 * A139446 A274918 A277736
Adjacent sequences: A144040 A144041 A144042 * A144044 A144045 A144046


KEYWORD

easy,nonn


AUTHOR

Raul Rato (rtrato(AT)yahoo.com), Sep 08 2008


EXTENSIONS

Removed initial terms that regarded 1 as a prime.  R. J. Mathar, Sep 11 2011
Comments edited by Zak Seidov, Jan 15 2014
Name changed (based on formula from Zak Seidov) by Jon E. Schoenfield, Oct 12 2015


STATUS

approved



