A048388 Replacing digits d in decimal expansion of n with d^2 yields a prime.

11, 13, 17, 19, 21, 27, 51, 57, 71, 73, 81, 87, 89, 91, 101, 103, 107, 119, 123, 129, 131, 133, 137, 149, 153, 161, 167, 169, 173, 189, 191, 197, 199, 201, 203, 207, 213, 223, 229, 231, 233, 249, 253, 267, 283, 307, 311, 313, 319, 321, 331, 337, 341, 359, 371

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1001 [offset shifted by Georg Fischer, Oct 14 2019]

Example

199 = (1)(9)(9) -> (1)(81)(81) = 18181 which is a prime.

Mathematica

Select[Range[400], PrimeQ[FromDigits[Flatten[IntegerDigits/@ (IntegerDigits[ #]^2)]]]&] (* Harvey P. Dale, Oct 13 2013 *)

Crossrefs

Cf. A048385, A048389.

Sequence in context: A138708 A061116 A333237 * A068191 A191599 A084374

Adjacent sequences: A048385 A048386 A048387 * A048389 A048390 A048391

Keyword

nonn,base

Author

Patrick De Geest, Mar 15 1999

Status

approved