A109948 Smallest prime == 1 (mod f(n)), where f(n) = concatenation n,n-1,...,3,2,1.

2, 43, 643, 51853, 108643, 3925927, 45925927, 525925927, 9876543211, 65925925927, 6665925925927, 1453331851851853, 1154657766913580249, 45219875551604938273, 7873482297771358024693, 742965003571105432098767

Offset

1,1

Links

Table of n, a(n) for n=1..16.

Mathematica

s = "1"; Do[s = ToString[n] <> s; k = ToExpression[s]; i = 1; While[ !PrimeQ[i*k + 1], i++ ]; Print[i*k + 1], {n, 2, 30}] (* Ryan Propper, Aug 01 2005 *)

Crossrefs

Cf. A109947.

Sequence in context: A220270 A240550 A142199 * A364556 A188683 A119775

Adjacent sequences: A109945 A109946 A109947 * A109949 A109950 A109951

Keyword

base,nonn

Author

Amarnath Murthy, Jul 20 2005

Extensions

More terms from Ryan Propper, Aug 01 2005

Status

approved