A139803 A033875(n) + 2^a(n) = A033875(n+1).

0, 1, 1, 2, 1, 2, 1, 2, 3, 4, 5, 2, 7, 4, 1, 2, 3, 4, 9, 2, 955, 468

Offset: 1

Author

Johan Särnbratt, May 22 2008

Keywords

• nonn
• more

Comments

a(23) > 10^4. - Zak Seidov, Jan 24 2017

a(23) > 30000 (if it exists). - Pontus von Brömssen, Jan 08 2023

Examples

			a(10) = 4 because A033875(10) = 31, 31 + 2^4 = 47, which is prime.
		

Crossrefs

Skipping from prime to prime by least powers of 2: A033875.

Cf. A059662, A067760.

Programs

Mathematica

p = 2; n = 0; While[true, x = 0; While[ ! PrimeQ[p + 2^x], x++ ]; p = p + 2^x; Print[x]; n++ ]

Formula

a(n) = A067760((A033875(n)-1)/2) for n >= 2. - Pontus von Brömssen, Jan 08 2023