The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A216426 Numbers of the form a^2*b^3, where a != b and a, b > 1. 2
 72, 108, 128, 200, 256, 288, 392, 432, 500, 512, 576, 648, 675, 800, 864, 968, 972, 1125, 1152, 1323, 1352, 1372, 1568, 1600, 1728, 1800, 1944, 2000, 2048, 2187, 2304, 2312, 2592, 2700, 2888, 2916, 3087, 3136, 3200, 3267, 3456, 3528, 3872, 3888, 4000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Terms of A216427 that are not 5th powers of squarefree numbers (A113850) and not 10th powers of primes (A030629). - Amiram Eldar, Feb 07 2023 LINKS Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 FORMULA Sum_{n>=1} 1/a(n) = 2 + ((zeta(2)-1)*(zeta(3)-1)-1)/zeta(6) - zeta(5)/zeta(10) - P(6) - P(10) = 0.09117811499514578262..., where P(s) is the prime zeta function. - Amiram Eldar, Feb 07 2023 MATHEMATICA With[{upto=4000}, Select[Union[Flatten[{#[[1]]^2 #[[2]]^3, #[[2]]^2 #[[1]]^3}& /@ Subsets[Range[2, Surd[upto, 2]], {2}]]], #<=upto&]](* Harvey P. Dale, Jan 04 2014 *) pMx = 25; mx = 2^3 pMx^2; t = Flatten[Table[If[a != b, a^2 b^3, 0], {a, 2, mx^(1/2)}, {b, 2, mx^(1/3)}]]; Union[Select[t, 0 < # <= mx &]] (* T. D. Noe, Jan 02 2014 *) PROG (PARI) list(lim)=my(v=List()); for(b=2, sqrtnint(lim\4, 3), for(a=2, sqrtint(lim\b^3), if(a!=b, listput(v, a^2*b^3)))); Set(v) \\ Charles R Greathouse IV, Jan 02 2014 CROSSREFS Cf. A143610. Subsequence of A216427. - Zak Seidov, Jan 03 2014 Cf. A002117, A013661, A013663, A013664, A013668, A030629, A085966, A113850. Sequence in context: A258695 A102562 A357460 * A308053 A356871 A359280 Adjacent sequences: A216423 A216424 A216425 * A216427 A216428 A216429 KEYWORD nonn AUTHOR V. Raman, Sep 07 2012 EXTENSIONS Name corrected by Charles R Greathouse IV, Jan 02 2014 STATUS approved

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

Last modified May 25 17:00 EDT 2024. Contains 372804 sequences. (Running on oeis4.)