A030144 Primes in which parity of digits alternates.

2, 3, 5, 7, 23, 29, 41, 43, 47, 61, 67, 83, 89, 101, 103, 107, 109, 127, 149, 163, 167, 181, 307, 347, 349, 367, 383, 389, 503, 509, 521, 523, 541, 547, 563, 569, 587, 701, 709, 727, 743, 761, 769, 787, 907, 929, 941, 947, 967, 983, 2129, 2141, 2143, 2161, 2309

Offset: 1

Author

Patrick De Geest

Keywords

• nonn
• base

Examples

			2129 is a term as 2, 1, 2 and 9 have even and odd parity alternately.
		

Links

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

Crossrefs

Intersection of A000040 and A030141.

Cf. A030143, A030152.

Programs

Haskell

a030144 n = a030144_list !! (n-1)
a030144_list = filter ((== 1) . a228710) a000040_list
-- Reinhard Zumkeller, Aug 31 2013

Mathematica

Join[{2,3,5,7},Select[Prime[Range[400]],Union[Abs[Differences[Boole/@ EvenQ[ IntegerDigits[#]]]]] == {1}&]] (* Harvey P. Dale, Jul 26 2011 *)

Formula

A010051(a(n)) * A228710(a(n)) = 1. - Reinhard Zumkeller, Aug 31 2013

Extensions

Offset corrected by Reinhard Zumkeller, Aug 31 2013