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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A244434 Numbers n such that A244433(n) does not belong to the set {A244433(n-1), A244433(n+1)}.

Original entry on oeis.org

2, 5, 6, 83
Offset: 1

Views

Author

Farideh Firoozbakht, Jul 19 2014

Keywords

Examples

			83 is a term of the sequence because A244433(83)=491702 does not belong to the set {A244433(82), A244433(84)}={424783, 860831}.

A244435 a(n) is the smallest number m such that 2*k*m - 1 is composite for all k, 0 < k < n+1.

Original entry on oeis.org

5, 13, 13, 62, 73, 73, 89, 118, 118, 118, 118, 118, 236, 926, 959, 959, 959, 959, 959, 959, 1063, 1474, 1474, 1474, 1667, 1667, 6118, 8249, 9098, 9098, 9098, 9098, 9098, 9098, 9098, 9098, 9098, 9098, 9098, 9098, 9098, 9098, 9098, 35573, 35573, 35573, 57448, 57448, 57448, 57448, 57448, 57448, 57448
Offset: 1

Views

Author

Farideh Firoozbakht, Jul 19 2014

Keywords

Comments

a(2)=a(3)=13, a(5)=a(6)=73, ... a(29)=a(30)=...=a(43)=9098, ... . A244436 gives numbers k such that a(k) is not in the set {a(k-1), a(k+1)}.

Links

Crossrefs

Cf. A124516, A244433, A244436.

Programs

  • Maple
    M:= 0: R:= NULL:
for m from 2 while M < 100 do
  for i from 0 while not isprime(2*i*m-1) do od:
  if i-1 > M then R:= R, m$(i-1-M); M:= i-1; fi;
od:
R; # Robert Israel, May 03 2021
  • PARI
    isok(n, m) = for(k=1, n, my(x=2*k*m-1); if ((x==1) || isprime(x), return(0))); return (1);
a(n) = my(m=1); while(!isok(n, m), m++); m; \\ Michel Marcus, May 04 2021
Showing 1-2 of 2 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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