This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A176885 Let p*q = A006881(n) be the n-th number that is the product of two distinct primes, with p = prime(i), q=prime(j); a(n) = p^j - q^i. 1
 1, 3, 9, 2, 32, 21, 51, 122, 111, 282, 237, 560, 489, 1898, 1794, 6200, 995, 2017, 13428, 19154, 4059, 2166, 8151, 73212, 16341, 58208, 89088, 176186, 32721, 383766, 65483, 530072, 1940958, 131013, 740022, 262083, 1592642, 4781120, 5634480, 524221 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS EXAMPLE For n=3, A006881(3) = 14 = 2*7, p=2, i=1, q=7, j=4; a(n) = 2^4-7^1 = 9. MAPLE A176885 := proc(n) c := A006881(n) ; pm := A020639(c) ; pk := A006530(c) ; pm^ numtheory[pi](pk) -pk^numtheory[pi](pm) ; end proc: seq(A176885(n), n=1..80) ; # R. J. Mathar, May 01 2010 CROSSREFS Cf. A006881. Sequence in context: A286676 A246379 A303941 * A257731 A257733 A098323 Adjacent sequences:  A176882 A176883 A176884 * A176886 A176887 A176888 KEYWORD nonn AUTHOR Juri-Stepan Gerasimov, Apr 28 2010 EXTENSIONS a(14) and a(15) corrected and sequence extended by R. J. Mathar, May 01 2010 Definition clarified by N. J. A. Sloane, Feb 16 2019 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 6 07:06 EST 2019. Contains 329784 sequences. (Running on oeis4.)