A114758 Smallest prime of the form: n successive positive integers in descending order followed by a 1.

11, 211, 5431, 76541, 17161514131, 1211109871, 98765431, 876543211, 9876543211, 242322212019181716151, 11109876543211, 1131121111101091081071061051041031021, 555453525150494847464544431

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..173

Example

a(4) = 76541, four successive positive integers 7,6,5,4 in descending order followed by a 1.

Maple

f:= proc(n) local k, p, j;
  for k from 0 do
    p:= parse(cat(seq(k+j, j=n .. 1, -1), 1));
    if isprime(p) then return p fi
  od
end proc:map(f, [$1..15]); # Robert Israel, Apr 03 2023

Mathematica

a[n_]:=(For[m=1, (v={}; Do[v=Join[v, IntegerDigits[k]], {k, m+n-1, m, -1}]); !PrimeQ[10FromDigits[v]+1], m++ ]; 10FromDigits[v]+1); Table[a[n], {n, 14}] (* Farideh Firoozbakht, Jan 02 2006 *)
f[n_] := Block[{t = Reverse@Range@n}, While[p = FromDigits@Flatten@IntegerDigits@Join[t, {1}]; ! PrimeQ@p, t++ ]; p]; Array[f, 13] (* Robert G. Wilson v, Jan 03 2006 *)

Crossrefs

Cf. A113514, A114754, A114755, A114756, A114757, A114759, A112716, A108145, A114761.

Sequence in context: A110747 A112704 A243674 * A088061 A070220 A134069

Adjacent sequences: A114755 A114756 A114757 * A114759 A114760 A114761

Keyword

base,nonn

Author

Amarnath Murthy, Jan 01 2006

Extensions

Extended by Robert G. Wilson v, Ray Chandler and Farideh Firoozbakht, Jan 02 2006

More terms from Robert G. Wilson v, Jan 03 2006

Status

approved