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 A061346 Odd numbers that are neither primes nor prime powers. 10
 15, 21, 33, 35, 39, 45, 51, 55, 57, 63, 65, 69, 75, 77, 85, 87, 91, 93, 95, 99, 105, 111, 115, 117, 119, 123, 129, 133, 135, 141, 143, 145, 147, 153, 155, 159, 161, 165, 171, 175, 177, 183, 185, 187, 189, 195, 201, 203, 205, 207, 209, 213, 215, 217, 219, 221 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Odd numbers with at least two distinct prime factors. - N. J. A. Sloane, Oct 15 2022 Odd leg of more than one primitive Pythagorean triangles. For smallest odd leg common to 2^n PPTs, see A070826. - Lekraj Beedassy, Jul 12 2006 Numbers that can be factored by Shor's algorithm. - Charles R Greathouse IV, Mar 05 2012 LINKS Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 FORMULA a(n) ~ 2n. - Charles R Greathouse IV, Aug 20 2012 MAPLE select(t -> nops(ifactors(t)[2]) > 1, [seq(2*i+1, i=1..1000)]); # Robert Israel, Dec 14 2014 MATHEMATICA Select[Range[1, 249, 2], Length[FactorInteger[#]] > 1 &] (* Alonso del Arte, Jan 30 2012 *) Select[ Range[1, 475, 2], PrimeNu@# > 1 &] (* Robert G. Wilson v, Dec 12 2014 *) PROG (ARIBAS): for k := 3 to 253 by 2 do ar := factorlist(k); if ar[0] < ar[length(ar)-1] then write(k, " ") end; end; (PARI) is(n)=ispower(n, , &n); n%2&&!isprime(n)&&n>1 \\ Charles R Greathouse IV, Jan 30 2012 (PARI) is(n)=n%2 && !isprimepower(n) && n>1 \\ Charles R Greathouse IV, May 06 2016 (PARI) count(x)=if(x<9, 0, (x\=1) - sum(k=1, logint(x, 3), primepi(sqrtnint(x, k)) - 1) - x\2 - 1) \\ Charles R Greathouse IV, Mar 06 2018 CROSSREFS Subsequence of A056911. A225375 is a subsequence. Cf. A061345. Sequence in context: A070005 A275384 A185307 * A098905 A225375 A329229 Adjacent sequences: A061343 A061344 A061345 * A061347 A061348 A061349 KEYWORD nonn,easy AUTHOR N. J. A. Sloane, Jun 08 2001 EXTENSIONS More terms from Klaus Brockhaus, Jun 10 2001 STATUS approved

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Last modified June 6 10:50 EDT 2023. Contains 363142 sequences. (Running on oeis4.)