A120805 Primes with consecutive digits.

2, 3, 5, 7, 23, 43, 67, 89, 109, 4567, 10987, 76543, 78901, 678901, 23456789, 45678901, 9012345678901, 789012345678901, 56789012345678901234567890123, 90123456789012345678901234567, 10987654321098765432109876543210987

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 A356271

Adjacent sequences: A120802 A120803 A120804 * A120806 A120807 A120808

Keyword

nonn,base

Author

Robert G. Wilson v, Jul 05 2006

Status

approved