A032691 Exactly 1 digit from {1,2,3,4,5,6,7,8,9} can precede a term to form a prime.

89, 107, 139, 141, 169, 189, 223, 249, 267, 313, 379, 383, 403, 453, 497, 587, 589, 633, 667, 751, 757, 763, 799, 859, 893, 899, 913, 959, 961, 977, 979, 981, 983, 989, 991, 1003, 1007, 1009, 1041, 1049, 1063, 1067, 1087, 1093, 1107, 1109, 1123, 1127

Offset

1,1

Links

Daniel Starodubtsev, Table of n, a(n) for n = 1..10000

Example

For term 1127, we find only '9'1127 to be prime.

Mathematica

aQ[n_] := Total@Boole@PrimeQ[Table[FromDigits[Prepend[IntegerDigits[n], i]], {i, 9}]] == 1; Select[Range[1130], aQ[#]&] (* Jayanta Basu, Jun 03 2013 *)

Prog

(Python)
from sympy import isprime
print([i for i in range(1000) if [isprime(int(j + str(i))) for j in '123456789'].count(True) == 1]) # Daniel Starodubtsev, Apr 06 2020

Crossrefs

Cf. A088602.

Sequence in context: A033254 A215165 A157764 * A146332 A146352 A050956

Adjacent sequences: A032688 A032689 A032690 * A032692 A032693 A032694

Keyword

nonn,base

Author

Patrick De Geest, May 15 1998

Status

approved