A133412 - OEIS

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A133412

Sum of primes between n-th and (n+1)-th semiprimes.

5, 7, 0, 24, 0, 36, 0, 23, 0, 60, 0, 0, 37, 0, 84, 47, 0, 53, 0, 0, 120, 0, 67, 144, 0, 79, 83, 0, 0, 89, 0, 0, 0, 301, 216, 113, 0, 0, 0, 0, 0, 127, 131, 0, 276, 0, 0, 0, 0, 300, 157, 0, 0, 163, 167, 173, 0, 360, 0, 0, 384, 396, 0, 0, 0, 0, 0, 211, 0, 0, 0, 0, 0, 0, 223, 689, 0, 480, 0

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..79.

EXAMPLE

a(1)=5 because between s(1)=4 and s(2)=6 there is one prime 5,

a(2)=7 because between s(2)=6 and s(3)=9 there is one prime 7,

a(3)=0 because between s(3)=9 and s(4)=10 there is no primes;

a(4)=24 because between s(4)=10 and s(5)=14 there are two primes 11 and 13 sum of which is 24, (s(n)=n-th semiprime).

MATHEMATICA

With[{sps=Partition[Select[Range[250], PrimeOmega[#]==2&], 2, 1]}, Total[ Select[ Range[ First[#], Last[#]], PrimeQ]]&/@sps] (* Harvey P. Dale, Sep 04 2011 *)

CROSSREFS

Sequence in context: A332328 A021950 A072417 * A111833 A011378 A329346

Adjacent sequences: A133409 A133410 A133411 * A133413 A133414 A133415

KEYWORD

nonn

AUTHOR

Zak Seidov, Dec 22 2007

STATUS

approved