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A183147 1 together with the numbers with property that at least two successive of their divisors are odd or even. 1
1, 3, 4, 5, 7, 8, 9, 11, 12, 13, 15, 16, 17, 19, 20, 21, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 39, 40, 41, 43, 44, 45, 47, 48, 49, 51, 52, 53, 55, 56, 57, 59, 60, 61, 63, 64, 65, 67, 68, 69, 70, 71, 72, 73, 75, 76, 77, 79, 80, 81, 83, 84, 85, 87, 88, 89, 90, 91, 92, 93, 95, 96, 97, 99, 100 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..78.

Wikipedia, Table of divisors

EXAMPLE

12 is in the sequence because its divisors are 1, 2, 3, 4, 6, 12 and then we can see that the successive divisors 4, 6, and 12 are even numbers.

MAPLE

isA183147 := proc(n)

        local di, i ;

        if n = 1 then

                return true;

        end if;

        di := sort(convert(numtheory[divisors](n), list)) ;

        for i from 1 to nops(di)-1 do

                if (op(i+1, di)-op(i, di)) mod 2 = 0 then

                        return true;

                end if;

        end do;

        return false;

end proc:

for n from 1 to 100 do

        if isA183147(n) then

                printf("%d, ", n);

        end if;

end do; # R. J. Mathar, Sep 30 2011

CROSSREFS

Complement of A182991, for n > 1.

Cf. A182996.

Sequence in context: A285958 A179779 A284679 * A074227 A122906 A042965

Adjacent sequences:  A183144 A183145 A183146 * A183148 A183149 A183150

KEYWORD

nonn,easy

AUTHOR

Omar E. Pol, Aug 04 2011

STATUS

approved

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Last modified February 19 22:04 EST 2020. Contains 332060 sequences. (Running on oeis4.)