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A120805 Primes with consecutive digits. 2
2, 3, 5, 7, 23, 43, 67, 89, 109, 4567, 10987, 76543, 78901, 678901, 23456789, 45678901, 9012345678901, 789012345678901, 56789012345678901234567890123, 90123456789012345678901234567, 10987654321098765432109876543210987 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Digits can be in ascending or descending order. After 9 comes 0 or after 0 comes 1.

The number of primes with n consecutive digits: 4,4,1,1,3,1,0,2,0,0,0,0,1,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,2,0,0,0,0,0,1,1,0,0,0,0,0,0,1,0,0,0,0,0,0,0,...,.

LINKS

Table of n, a(n) for n=1..21.

MATHEMATICA

f[n_] := Block[{u = Range@n, d = Reverse@ Range@n, t = Table[1, {n}]}, Select[ Drop[ Union@ Flatten@ Table[ FromDigits /@ Mod[{u, d} + {i*t, i*t}, 10], {i, 10}], 2], PrimeQ@# &]]; Array[f, 35] // Flatten

CROSSREFS

Cf. A000040, A118697; union of A006055 & A120804.

Sequence in context: A048398 A059170 A068710 * A177119 A096265 A056041

Adjacent sequences:  A120802 A120803 A120804 * A120806 A120807 A120808

KEYWORD

nonn,base

AUTHOR

Robert G. Wilson v, Jul 05 2006

STATUS

approved

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Last modified September 25 16:31 EDT 2017. Contains 292499 sequences.