login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A257999 Numbers of the form, 2^i*3^j, i+j odd. 3
2, 3, 8, 12, 18, 27, 32, 48, 72, 108, 128, 162, 192, 243, 288, 432, 512, 648, 768, 972, 1152, 1458, 1728, 2048, 2187, 2592, 3072, 3888, 4608, 5832, 6912, 8192, 8748, 10368, 12288, 13122, 15552, 18432, 19683, 23328, 27648, 32768, 34992, 41472, 49152, 52488 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

FORMULA

A069352(a(n)) mod 2 = 1.

Sum_{n>=1} 1/a(n) = 5/4. - Amiram Eldar, Feb 18 2021

MATHEMATICA

max = 53000; Reap[Do[k = 2^i*3^j; If[k <= max && OddQ[i + j], Sow[k]], {i, 0, Log[2, max] // Ceiling}, {j, 0, Log[3, max] // Ceiling}]][[2, 1]] // Union (* Amiram Eldar, Feb 18 2021 after Jean-Fran├žois Alcover at A036667 *)

PROG

(Haskell)

a257999 n = a257999_list !! (n-1)

a257999_list = filter (odd . flip mod 2 . a001222) a003586_list

CROSSREFS

Complement of A036667 with respect to A003586.

Intersection of A026424 and A003586.

Cf. A069352, A022328, A022329.

Sequence in context: A266629 A249096 A249367 * A115449 A303851 A218542

Adjacent sequences:  A257996 A257997 A257998 * A258000 A258001 A258002

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, May 16 2015

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 14 19:28 EDT 2021. Contains 345038 sequences. (Running on oeis4.)