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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A256302 Least prime p such that p+3*k*(k+1) is prime for all k=0,...,n.

Original entry on oeis.org

2, 5, 5, 5, 11, 11, 11, 11, 11, 11, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23
Offset: 0

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Author

M. F. Hasler, Apr 05 2015

Keywords

Comments

Inspired by the so-called prime-generating polynomials.
Since p | 3n(n+1) for n=p-1, one has a(n) > p(n). Otherwise stated, a(p-1) = p (as, e.g., for p=23) is optimal.

Crossrefs

Cf. A181963, A181969, A181973, A210626, A211773, A212325, ...
Cf. A005846, A056561.
Cf. A256300, A256301.

Programs

  • PARI
    a(n)=forprime(p=1,,for(i=1,n,ispseudoprime(p+3*(i+1)*i)||next(2));return(p))
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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