A078832 Smallest prime contained as binary substring in binary representation of n>1, a(1)=1.

1, 2, 3, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2

Offset: 1

Author

Reinhard Zumkeller, Dec 08 2002

Keywords

• nonn
• base

Comments

a(n)<=3 and for n>1: a(n)>=2 and a(n)=3 iff n=2^k-1, k>1.

a(n) = A225243(n,1). - Reinhard Zumkeller, Aug 14 2013

Links

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

Crossrefs

Cf. A078833, A078826, A078822, A007088, A020639.

Cf. A030308, A010051, A000225.

Programs

Haskell

a078832 = head . a225243_row  -- Reinhard Zumkeller, Aug 14 2013

Formula

For n > 1: a(n) = A036987(n) + 2. Reinhard Zumkeller, Aug 14 2013