

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
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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



