|
| |
|
|
A112716
|
|
Smallest prime of the form: n successive positive integers in descending order followed by a 7.
|
|
7
| |
|
|
17, 547, 3217, 65437, 543217, 8765437, 76543217, 41403938373635347, 9876543217, 282726252423222120197, 1312111098765437, 2322212019181716151413127, 222120191817161514131211107, 1615141312111098765437
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
EXAMPLE
| a(4) = 65437, four successive positive integers 6,5,4,3 in descending order followed by a 7.
|
|
|
MATHEMATICA
| a[n_]:=(For[m=1, (v={}; Do[v=Join[v, IntegerDigits[k]], {k, m+n-1, m, -1}]); !PrimeQ[10FromDigits[v]+7], m++ ]; 10FromDigits[v]+7); Table[a[n], {n, 14}] - Farideh Firoozbakht
f[n_] := Block[{t = Reverse@Range@n}, While[p = FromDigits@Flatten@IntegerDigits@Join[t, {7}]; !PrimeQ@p, t++ ]; p]; Array[f, 14] (* Robert G. Wilson v *)
|
|
|
CROSSREFS
| Cf. A114754, A114755, A114756, A114757, A114758, A114759, A108145.
Sequence in context: A012232 A114063 A193120 * A197395 A012069 A191865
Adjacent sequences: A112713 A112714 A112715 * A112717 A112718 A112719
|
|
|
KEYWORD
| base,nonn
|
|
|
AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jan 01 2006
|
|
|
EXTENSIONS
| Extended by Robert G. Wilson v (rgwv(at)rgwv.com), Ray Chandler (rayjchandler(AT)sbcglobal.net) and Farideh Firoozbakht (mymontain(AT)yahoo.com), Jan 02 2006
|
| |
|
|
