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A248554
Numbers k such that the sum of the digital roots of the first k primes is also prime; increasingly sorted.
1
1, 2, 4, 5, 6, 7, 9, 11, 17, 37, 41, 47, 59, 61, 79, 85, 87, 98, 104, 109, 112, 126, 132, 141, 142, 143, 151, 152, 158, 173, 183, 184, 191, 192, 204, 208, 210, 212, 215, 221, 226, 227, 236, 243, 251, 256, 274, 279, 306, 314, 325, 334, 356, 365, 375, 382, 387, 401, 403, 419, 437, 452, 473, 483, 488
OFFSET
1,2
LINKS
EXAMPLE
The sum of the digital roots of the first four primes is prime (2+3+5+7=17), therefore 4 is in the sequence.
MATHEMATICA
Select[Range[1000], PrimeQ[Sum[Mod[Prime[i], 9], {i, 1, #}]]&]
CROSSREFS
Sequence in context: A164317 A138620 A260820 * A346993 A098166 A217445
KEYWORD
base,easy,nonn
AUTHOR
Ivan N. Ianakiev, Oct 08 2014
EXTENSIONS
Edited. Name specified. - Wolfdieter Lang, Oct 30 2014
STATUS
approved