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A128760 Number of ways to write n as the absolute difference of a power of 2 and a power of 3. 3
1, 4, 1, 1, 0, 3, 0, 3, 1, 0, 0, 1, 0, 2, 0, 1, 0, 1, 0, 1, 0, 0, 0, 2, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

a(A014121(n)) > 0; the only even numbers m with a(m)>0 are of the form m=3^k-1: a(A024023(n)) > 0;

Conjecture: there exists c>=23 such that a(n)<2 for n>c.

LINKS

Max Alekseyev, Table of n, a(n) for n = 0..1000

EXAMPLE

a(1) = #{2^1 - 3^0, 2^2 - 3^1, 3^1 - 2^1, 3^2 - 2^3} = 4;

a(2) = #{3^1 - 2^0} = 1;

a(3) = #{2^2 - 3^0} = 1;

a(5) = #{2^3 - 3^1, 2^5 - 3^3, 3^2 - 2^2} = 3;

a(7) = #{2^3 - 3^0, 2^4 - 3^2, 3^2 - 2^1} = 3;

a(8) = #{3^2 - 2^0} = 1;

a(11) = #{3^3 - 2^4} = 1;

a(13) = #{2^4 - 3^1, 2^8 - 3^5} = 2;

a(15) = #{2^4 - 2^0} = 1;

a(17) = #{3^4 - 2^6} = 1;

a(19) = #{3^3 - 2^3} = 1;

a(23) = #{2^5 - 3^2, 3^3 - 2^2} = 2;

a(25) = #{3^3 - 2^1} = 1.

CROSSREFS

Cf. A000079, A000244.

Sequence in context: A158972 A278987 A135302 * A057884 A329637 A276834

Adjacent sequences:  A128757 A128758 A128759 * A128761 A128762 A128763

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Mar 25 2007

STATUS

approved

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Last modified June 14 02:26 EDT 2021. Contains 345016 sequences. (Running on oeis4.)