A143015 a(1) = 1. a(n) = the smallest integer >=2 such that (product{k=1 to n} a(k)) in binary is a palindrome.

1, 3, 3, 3, 7, 13, 5, 13, 57, 223, 5419, 17, 241, 4192257, 16773121, 17, 241

Offset

1,2

Comments

All terms are odd.

There are an infinite number of terms.

a(18) > 11000000001. - Robert G. Wilson v, Jun 30 2009

Links

Table of n, a(n) for n=1..17.

Formula

For n>=2, a(n) = A143014(n)/A143014(n-1).

Mathematica

f[n_] := f[n] = Block[{k = 3, a = Times @@ Table[ f@i, {i, n - 1}]}, While[ id = IntegerDigits[a*k, 2]; id != Reverse@id, k += 2]; k]; f[1]=1; Array[f, 17] (* Robert G. Wilson v, Jun 30 2009 *)

Crossrefs

Cf. A143014, A143016.

Sequence in context: A342335 A137438 A098524 * A295671 A107709 A111521

Adjacent sequences: A143012 A143013 A143014 * A143016 A143017 A143018

Keyword

base,more,nonn

Author

Leroy Quet, Jul 15 2008

Extensions

a(6)-a(17) from Ray Chandler, Jun 21 2009

Status

approved