A085815 Least k such that A056830(n) + k is prime, where A056830 = alternate digits 1 and 0.

2, 1, 1, 0, 3, 2, 11, 28, 13, 12, 29, 62, 1, 10, 1, 30, 27, 40, 73, 42, 63, 90, 29, 8, 61, 120, 37, 20, 41, 20, 1, 66, 283, 66, 27, 146, 1, 222, 1, 8, 77, 190, 173, 18, 1, 50, 149, 50, 29, 66, 31, 26, 23, 10, 29, 150, 99, 330, 81, 356, 53, 102, 7, 126, 123, 10, 227, 526, 117, 96

Offset: 0

Author

Jason Earls, Jul 25 2003

Keywords

• nonn
• base

Examples

			a(7)=28 because 1010101 + 28 = 1010129, a prime.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 0..500

Programs

Mathematica

Table[Module[{k=0,d=FromDigits[PadRight[{},n,{1,0}]]},While[!PrimeQ[d+k],k++];k],{n,0,70}] (* Harvey P. Dale, Jul 14 2025 *)