A075806 Differences between adjacent palindromic numbers which are products of an odd number of distinct primes.

1, 2, 2, 4, 55, 35, 30, 20, 30, 10, 31, 60, 31, 40, 20, 10, 51, 40, 20, 61, 40, 11, 40, 81, 30, 20, 10, 10, 122, 10, 40, 32, 220, 330, 220, 451, 660, 451, 220, 781, 660, 341, 220, 110, 220, 110, 11, 220, 220, 440, 451, 220, 110, 110, 110, 451, 220, 220, 220, 341

Offset: 1

Author

Jani Melik, Oct 13 2002

Keywords

• nonn
• base

Examples

			a(1)=3-2=1, a(2)=5-3=2, a(5)=66-11=55.
		

Links

• Paolo Xausa, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A037010.

First differences of A075800.

Programs

Maple

test := proc(n) local d; d := convert(n,base,10); return ListTools[Reverse](d)=d and numtheory[mobius](n)=-1; end; s := []; for n from 1 to 11000 do if test(n) then s := [op(s),n]; end; od; a := [op(2..-1,s)-op(1..-2,s)];

Mathematica

Differences[Select[Range[10000], PalindromeQ[#] && MoebiusMu[#] == -1 &]] (* Paolo Xausa, Mar 10 2025 *)

Extensions

Edited by Dean Hickerson, Oct 21 2002