This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A249263 Primitive, odd, squarefree abundant numbers. 6
 15015, 19635, 21945, 23205, 25935, 26565, 31395, 33495, 33915, 35805, 39585, 41055, 42315, 42735, 45885, 47355, 49665, 50505, 51765, 54285, 55965, 58695, 61215, 64155, 68145, 70455, 72345, 77385, 80535, 82005, 83265, 84315, 91245, 95865, 102795, 112035, 116655, 118965 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The subsequence of primitive terms (not multiples of smaller terms) of A112643. The subsequence of squarefree terms of A006038. The subsequence of odd terms of A249242. Not the same as A129485. Does not contain, for example, 195195, 255255, 285285, 333795, 345345, 373065, which are in A129485. - R. J. Mathar, Nov 09 2014 Sequences A287590, A188342 and A287581 list the number, smallest* and largest of all squarefree odd primitive abundant numbers with n prime factors. (*At least whenever A188342(n) is squarefree, which appears to be the case for all n >= 5.) - M. F. Hasler, May 29 2017 LINKS Giovanni Resta, Table of n, a(n) for n = 1..10000 MAPLE # see A112643 and A006038 for the coding of isA112643 and isA006038 isA249263 := proc(n)     isA112643(n) and isA006038(n) ; end proc: for n from 1 do     if isA249263(n) then         print(n);     end if; end do: # R. J. Mathar, Nov 10 2014 PROG (PARI) v=[]; for(k=1, 10^5, n=2*k+1; if(issquarefree(n) && sigma(n)>2*n, for(i=1, #v, n%v[i] || next(2)); print1(n, ", "); v=concat(v, n))) \\ Improved (from 20 sec to 0.2 sec) by M. F. Hasler, May 27 2017 CROSSREFS Intersection of A112643 and A006038. Cf. A249242, A129485. Cf. A188342 (least with n factors), A287581 (largest with n factors), A287590 (number of terms with n factors). Sequence in context: A046391 A112643 A129485 * A294026 A133778 A200090 Adjacent sequences:  A249260 A249261 A249262 * A249264 A249265 A249266 KEYWORD nonn AUTHOR Derek Orr, Oct 23 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 | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified March 19 00:24 EDT 2019. Contains 321306 sequences. (Running on oeis4.)