cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A108614 Semiprimes with non-semiprimes digits (no digits 4,6,9 in semiprimes).

Original entry on oeis.org

10, 15, 21, 22, 25, 33, 35, 38, 51, 55, 57, 58, 77, 82, 85, 87, 111, 115, 118, 121, 122, 123, 133, 155, 158, 177, 178, 183, 185, 187, 201, 202, 203, 205, 213, 215, 217, 218, 221, 235, 237, 253, 278, 287, 301, 302, 303, 305, 321, 323, 327, 335, 355, 358, 371
Offset: 1

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Author

Zak Seidov, Jun 13 2005

Keywords

Comments

Complement of A107342 in the class of semiprimes.
This is to semiprimes A001358 as A034844 (Primes with nonprime digits) is to primes A000040. [Jonathan Vos Post, Jul 15 2010]

Crossrefs

Cf. A107342, A137167.
Cf. A107665, A107666, A111494, A111496, A111697, A179336. [Jonathan Vos Post, Jul 15 2010]

Programs

  • Mathematica
    cnd[n_]:=Plus@@Last/@FactorInteger[n]==2&&Union[FreeQ[IntegerDigits[n], # ]&/@{4, 6, 9}]=={True};Select[Range[600], cnd[ # ]&]

Formula

{j in A001358 and j not in A179463}. [Jonathan Vos Post, Jul 15 2010]
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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