A102249 Numbers k such that k1111 is prime.

10, 13, 31, 36, 51, 57, 61, 69, 72, 78, 79, 90, 91, 97, 117, 120, 127, 129, 135, 138, 153, 156, 166, 174, 183, 184, 189, 201, 205, 210, 222, 225, 226, 234, 237, 240, 241, 244, 252, 261, 265, 273, 276, 280, 285, 292, 304, 306, 309, 318, 322, 325, 327, 337, 345

Offset

1,1

Links

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

Example

At k=10, k1111 = 101111 (prime).
At k=90, k1111 = 901111 (prime).
At k=138, k1111 = 1381111 (prime).

Mathematica

Select[ Range[ 350], PrimeQ[ FromDigits[ Flatten[ IntegerDigits /@ { #, 1, 1, 1, 1}]]] &] (* Robert G. Wilson v, Feb 21 2005 *)
Select[Range[400], PrimeQ[#*10^4+1111]&] (* Harvey P. Dale, Jul 14 2019 *)

Crossrefs

Cf. A024912.

Sequence in context: A126973 A220045 A101215 * A195313 A219829 A062370

Adjacent sequences: A102246 A102247 A102248 * A102250 A102251 A102252

Keyword

nonn,base

Author

Parthasarathy Nambi, Feb 18 2005

Extensions

More terms from Robert G. Wilson v, Feb 21 2005

Status

approved