A084995 Numbers which can be written as the product of two different primes and the sum of digits is also prime.

14, 21, 34, 38, 58, 65, 74, 85, 94, 106, 111, 115, 119, 122, 133, 142, 146, 155, 166, 201, 203, 205, 209, 214, 218, 221, 247, 254, 265, 274, 278, 287, 298, 302, 319, 326, 335, 346, 355, 362, 371, 377, 382, 386, 391, 395, 403, 407, 427, 445, 454, 458, 469, 478, 481, 485

Offset

1,1

Links

Andrew Howroyd, Table of n, a(n) for n = 1..1000

Formula

Intersection of A028834 and A006881. - Andrew Howroyd, Jan 05 2020

Example

E.g., 14 = 7*2 and 1+4 = 5 is also prime.

Mathematica

Module[{nn=60}, Select[Union[Times@@@Subsets[Prime[Range[nn]], {2}]], PrimeQ[ Total[ IntegerDigits[#]]]&&#<=2Prime[nn]&]] (* Harvey P. Dale, Feb 28 2022 *)

Prog

(PARI) is(n)={bigomega(n)==2 && !issquare(n) && isprime(sumdigits(n))}
select(is, [1..500]) \\ Andrew Howroyd, Jan 05 2020

Crossrefs

Cf. A006881, A028834, A108606.

Sequence in context: A121495 A263990 A253810 * A100466 A100467 A082802

Adjacent sequences: A084992 A084993 A084994 * A084996 A084997 A084998

Keyword

nonn,base

Author

Meenakshi Srikanth (menakan_s(AT)yahoo.com), Jun 30 2003

Extensions

Terms a(14) and beyond from Andrew Howroyd, Jan 05 2020

Status

approved