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A120825
Number of digits of primes with n consecutive digits ascending beginning with the digit seven.
8
OFFSET
1,2
COMMENTS
Digits are in ascending order beginning with 7 and after 9 comes 0.
The sequence "Primes with n consecutive digits descending beginning with the digit seven" has only two terms below 6001, namely 1 and 5, which represent the primes 7 and 76543, respectively.
EXAMPLE
1 is here because 7 is prime.
5 is here because 78901 is prime.
15 is here because 789012345678901 is a prime.
51 is here because 789012345678901234567890123456789012345678901234567 is prime.
MATHEMATICA
fQ[n_] := PrimeQ@ FromDigits@ Mod[6+Range@n, 10]; lst = {}; Do[ If[fQ@n, AppendTo[lst, n]; Print@n], {n, 5000}]; lst
KEYWORD
base,hard,nonn
AUTHOR
Robert G. Wilson v, Jul 05 2006
STATUS
approved