A067208 n is prime and remains prime when its leading digit is increased by one.

2, 13, 19, 31, 37, 43, 61, 73, 79, 97, 127, 139, 151, 157, 163, 181, 193, 211, 283, 331, 349, 367, 379, 409, 421, 457, 463, 487, 499, 541, 547, 577, 601, 619, 643, 661, 673, 709, 727, 739, 757, 787, 811, 829, 853, 877, 883, 919, 991, 997, 1039, 1063, 1069

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

Increasing the leading digit of 97 (prime) by one yields 107 (prime). Hence 97 is a term of the sequence.

Mathematica

f[n_] := Block[{a = IntegerDigits[n] }, a[[1]] = a[[1]] + 1; Return[ FromDigits[a]]]; Select[ Range[1100], PrimeQ[ # ] && PrimeQ[ f[ # ]] & ]
Select[Prime[Range[200]], PrimeQ[FromDigits[Join[{IntegerDigits[#][[1]]+1}, Rest[IntegerDigits[#]]]]]&] (* or *) Select[Prime[ Range[ 200]], PrimeQ[#+10^(IntegerLength[#]-1)]&] (* Harvey P. Dale, Dec 27 2024 *)

Crossrefs

Sequence in context: A168672 A297854 A298089 * A142348 A309663 A347259

Adjacent sequences: A067205 A067206 A067207 * A067209 A067210 A067211

Keyword

base,easy,nonn,changed

Author

Joseph L. Pe, Feb 19 2002

Extensions

Edited and extended by Robert G. Wilson v, Feb 21 2002

Status

approved