A078403 - OEIS

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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

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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 *)