A078403 Primes whose digital root (A038194) is prime.

2, 3, 5, 7, 11, 23, 29, 41, 43, 47, 59, 61, 79, 83, 97, 101, 113, 131, 137, 149, 151, 167, 173, 191, 223, 227, 239, 241, 257, 263, 277, 281, 293, 311, 313, 317, 331, 347, 349, 353, 367, 383, 389, 401, 419, 421, 439, 443, 457, 461, 479, 491, 509, 547, 563, 569

Offset

1,1

Comments

Union of A061238, A061240, A061241 and 3. - Ya-Ping Lu, Jan 03 2024

Links

Table of n, a(n) for n=1..56.

Example

59 is a term because 5+9=14, giving (final) iterated sum 1+4=5 and 5 is prime.

Mathematica

Select[ Range[580], PrimeQ[ # ] && PrimeQ[Mod[ #, 9]] &]
Select[Prime[Range[200]], PrimeQ[Mod[#, 9]]&] (* Harvey P. Dale, Aug 20 2017 *)

Prog

(PARI) forprime(p=2, 997, if(isprime(p%9), print1(p, ", ")))
(Python) from sympy import isprime, primerange; [print(p, end = ', ') for p in primerange(2, 570) if isprime(p%9)] # Ya-Ping Lu, Jan 03 2024

Crossrefs

Cf. A038194, A061238, A061240, A061241, A070027, A078400.

Sequence in context: A376236 A317479 A087521 * A129945 A046704 A367793

Adjacent sequences: A078400 A078401 A078402 * A078404 A078405 A078406

Keyword

base,easy,nonn

Author

N. J. A. Sloane, Dec 26 2002

Extensions

Extended by Robert G. Wilson v, Klaus Brockhaus and Rick L. Shepherd, Dec 27 2002

Status

approved