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A239656 First differences of sphenic numbers, cf. A007304. 5
12, 24, 4, 8, 24, 3, 5, 4, 16, 8, 16, 11, 5, 4, 8, 4, 4, 5, 27, 8, 1, 7, 8, 9, 3, 8, 7, 9, 3, 1, 4, 20, 8, 4, 23, 9, 3, 9, 4, 4, 11, 14, 3, 4, 4, 8, 8, 3, 1, 4, 1, 3, 4, 13, 10, 5, 4, 9, 11, 4, 8, 12, 12, 4, 21, 6, 13, 8, 8, 5, 3, 4, 4, 3, 1, 5, 3, 9, 11, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) = A007304(n+1) - A007304(n);

see A239673 and A239674 for record values and where they occur: A239673(n) = a(A239674(n)).

LINKS

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

MAPLE

A007304 := proc(n)

    option remember;

    if n = 1 then

        30;

    else

        for a from procname(n-1)+1 do

            if numtheory[bigomega](a) =3 and nops(numtheory[factorset](a)) = 3 then

                return a;

            end if;

        end do:

    end if;

end proc:

A239656 := proc(n)

    A007304(n+1)-A007304(n) ;

end proc:

MATHEMATICA

With[{upto=1000}, Differences[Sort[Select[Times@@@Subsets[Prime[ Range[ Ceiling[upto/6]]], {3}], #<=upto&]]]] (* Harvey P. Dale, Jan 08 2015 *)

PROG

(Haskell)

a239656 n = a239656_list !! (n-1)

a239656_list = zipWith (-) (tail a007304_list) a007304_list

CROSSREFS

Cf. A065516.

Sequence in context: A255766 A015447 A072822 * A059161 A133491 A075606

Adjacent sequences:  A239653 A239654 A239655 * A239657 A239658 A239659

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Mar 23 2014

STATUS

approved

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Last modified February 24 00:38 EST 2020. Contains 332195 sequences. (Running on oeis4.)