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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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A240748 Numbers n such that n^k - (n-1)^k - ... - 3^k - 2^k - 1 is prime for some k.

Original entry on oeis.org

2, 4, 5, 6, 10, 13
Offset: 1

Views

Author

Derek Orr, Apr 11 2014

Keywords

Comments

a(7) > 13. See A240747 for more information.
a(n) is also the n-values such that A240747(n) is nonzero.
It is known that a(n) == 1 mod 4 or 2 mod 4 (except a(2) = 4).
If n is not squarefree, then n is not a member of this sequence.
It is known that 17, 22, 30, 41, 66, and 194 are members of this sequence.

Examples

			There are primes of the form 2^k-1 (A000043) so 2 is a member of this sequence.

Crossrefs

Cf. A000043, A240747, A240507, A240503.

Programs

  • PARI
    s(n) = for(k=1,6000,if(ispseudoprime(n^k-sum(i=1,n-1,i^k)),return(k)))
n=1; while(n<200,if(s(n),print(n));n+=1)
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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