The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A133412 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing all changes.

A133412

Sum of primes between n-th and (n+1)-th semiprimes.
(history; published version)

#5 by Charles R Greathouse IV at Thu Nov 21 12:49:07 EST 2013

MATHEMATICA

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

Discussion

Thu Nov 21

12:49

OEIS Server: https://oeis.org/edit/global/2062

#4 by Russ Cox at Fri Mar 30 17:26:23 EDT 2012

AUTHOR

_Zak Seidov (zakseidov(AT)yahoo.com), _, Dec 22 2007

Discussion

Fri Mar 30

17:26

OEIS Server: https://oeis.org/edit/global/139

#3 by Harvey P. Dale at Sun Sep 04 15:46:01 EDT 2011

STATUS

editing

approved

#2 by Harvey P. Dale at Sun Sep 04 15:45:55 EDT 2011

MATHEMATICA

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

STATUS

approved

editing

#1 by N. J. A. Sloane at Sun Jun 29 03:00:00 EDT 2008

NAME

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

DATA

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

OFFSET

1,1

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).

KEYWORD

nonn

AUTHOR

Zak Seidov (zakseidov(AT)yahoo.com), Dec 22 2007

STATUS

approved