A030145 Primes such that in p^2 the parity of digits alternates.

2, 3, 5, 7, 11, 13, 19, 23, 31, 113, 127, 137, 181, 269, 277, 281, 311, 461, 463, 661, 673, 677, 1019, 1277, 1361, 1973, 2287, 2339, 2377, 2411, 2423, 2689, 2731, 4673, 5023, 5081, 5261, 6563, 6577, 8311, 9013, 9437, 9439, 10181, 10463

Offset: 1

Author

Patrick De Geest

Keywords

• nonn
• base

Links

• Giovanni Resta, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A030144, A030146, A030151.

Programs

Mathematica

id[n_]:=IntegerDigits[n]; t={}; Do[p=Prime[n]; If[Length[id[p]]==1,AppendTo[t,p], If[Union[Abs[Differences[Boole/@EvenQ[id[p^2]]]]]=={1}, AppendTo[t,p]]], {n,1300}]; t (* Jayanta Basu, May 07 2013 *)
pdaQ[n_]:=FreeQ[Differences[Boole[EvenQ[IntegerDigits[n^2]]]],0]; Select[ Prime[ Range[1300]],pdaQ] (* Harvey P. Dale, Jul 30 2019 *)

Formula

a(n)^2 = A030146(n). - Giovanni Resta, Aug 16 2018

Extensions

Offset corrected by Giovanni Resta, Aug 16 2018