A121889 Least m such that (prime(n) mod m) > (prime(n+1) mod m).

3, 4, 3, 5, 3, 5, 3, 5, 4, 3, 4, 5, 3, 5, 4, 7, 3, 7, 5, 3, 7, 5, 4, 3, 5, 3, 5, 3, 5, 3, 5, 4, 3, 4, 3, 4, 7, 5, 4, 7, 3, 7, 3, 5, 3, 5, 13, 5, 3, 5, 7, 3, 11, 4, 7, 4, 3, 4, 5, 3, 4, 3, 5, 3, 5, 3, 4, 11, 3, 5, 7, 3, 4, 7, 5, 4, 3, 5, 3, 11, 3, 11, 3, 7, 5, 4, 3, 5, 3, 5, 7, 3, 5, 3, 5, 4, 5, 3, 4, 7, 4, 7, 4

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

a(100) = 7 because prime(100) = 541 == 2 mod 7, prime(101) = 547 == 1 mod 7 and 7 is least m such that 541 > 547 mod m.

Maple

g:= proc(a, b) local m;
     for m from 2 do if (a mod m) > (b mod m) then return m fi od
end proc:
seq(g(ithprime(i), ithprime(i+1)), i=1..200); # Robert Israel, May 20 2026

Mathematica

s={}; Do[pn=Prime[n]; pn1=Prime[n+1]; Do[If[Mod[pn, m]>Mod[pn1, m], AppendTo[s, {n, pn, pn1, m}]; Break[]], {m, 2, 200}], {n, 1, 130}]; Last/@s
lm[n_]:=Module[{m=2, pn0=Prime[n], pn1=Prime[n+1]}, While[Mod[pn0, m]<= Mod[ pn1, m], m++]; m]; Array[lm, 110] (* Harvey P. Dale, May 27 2014 *)

Crossrefs

Sequence in context: A076400 A363194 A388044 * A332026 A205692 A342927

Adjacent sequences: A121886 A121887 A121888 * A121890 A121891 A121892

Keyword

nonn

Author

Zak Seidov, Aug 31 2006

Status

approved