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A343412
Numbers k such that k + A000203(k) + A001414(A000203(k)) is prime.
2
1, 3, 8, 14, 17, 18, 28, 31, 42, 55, 59, 65, 82, 83, 88, 95, 97, 104, 112, 113, 118, 119, 123, 127, 131, 142, 147, 177, 180, 185, 186, 204, 207, 215, 218, 220, 243, 246, 253, 257, 263, 270, 274, 280, 286, 287, 299, 330, 332, 334, 335, 339, 343, 354, 365, 372, 379, 381, 384, 388, 392, 400, 413
OFFSET
1,2
LINKS
EXAMPLE
a(3) = 8 is a term because A000203(8) = 15 = 3*5 and 8+15+(3+5) = 31 is prime.
MAPLE
filter:= proc(n) local s; s:= numtheory:-sigma(n);
isprime(n + s + add(t[1]*t[2], t=ifactors(s)[2]))
end proc:
CROSSREFS
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Apr 14 2021
STATUS
approved