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A193304 Squarefree numbers multiplied by powers of 5. 2
1, 2, 3, 5, 6, 7, 10, 11, 13, 14, 15, 17, 19, 21, 22, 23, 25, 26, 29, 30, 31, 33, 34, 35, 37, 38, 39, 41, 42, 43, 46, 47, 50, 51, 53, 55, 57, 58, 59, 61, 62, 65, 66, 67, 69, 70, 71, 73, 74, 75, 77, 78, 79, 82, 83, 85, 86, 87, 89, 91, 93, 94, 95, 97, 101, 102, 103, 105, 106, 107, 109, 110, 111, 113, 114, 115, 118, 119, 122, 123, 125, 127, 129, 130, 131, 133, 134, 137, 138, 139, 141, 142, 143, 145, 146, 149, 150, 151, 154, 155, 157, 158, 159, 161, 163, 165, 166, 167, 170 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers k such that A008683(A132739(k)) is not zero, where A008683 is the Moebius mu function. - Antti Karttunen, Jun 21 2014

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10000

FORMULA

a(n) ~ kn with k = 10*Pi^2/63. - Charles R Greathouse IV, Apr 16 2015

MAPLE

N:= 1000: # to get all terms <= N

sf:= select(numtheory:-issqrfree, {$1..N}):

map(t -> seq(t*5^i, i=0..floor(log[5](N/t))), sf);

# if using Maple 11 or earlier, uncomment the next line

# sort(convert(%, list)); # Robert Israel, Apr 16 2015

MATHEMATICA

lim = 102; sf = Select[Range[lim], SquareFreeQ]; lim5 = 5^Range[0, Log[5, lim]]; Select[Union[Flatten[Outer[Times, sf, lim5]]], # <= lim &]

PROG

(PARI) is(n)=issquarefree(n/5^valuation(n, 5)) \\ Charles R Greathouse IV, Jul 31 2011

(Scheme, with Antti Karttunen's IntSeq-library)

(define A193304 (NONZERO-POS 1 1 (COMPOSE A008683 A132739)))

;; Reflecting essentially the above Pari-program, Antti Karttunen, Jun 21 2014

CROSSREFS

Differs from A240370 for the first time at n=109, where A240370(109)=169, while here it is missing, and a(109)=170.

Cf. A008683, A132739.

Sequence in context: A064594 A325511 A240370 * A076144 A005117 A144338

Adjacent sequences:  A193301 A193302 A193303 * A193305 A193306 A193307

KEYWORD

nonn

AUTHOR

José María Grau Ribas, Jul 21 2011

STATUS

approved

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Last modified October 17 08:36 EDT 2019. Contains 328107 sequences. (Running on oeis4.)