A189481 Numbers n such that x' = n has a unique solution, where x' denotes the arithmetic derivative (A003415).

4, 5, 6, 7, 8, 9, 13, 15, 19, 25, 27, 33, 41, 43, 49, 51, 59, 63, 69, 73, 77, 85, 95, 99, 105, 109, 113, 115, 121, 133, 135, 139, 141, 143, 153, 155, 159, 161, 169, 171, 175, 181, 187, 193, 201, 203, 225, 227, 229, 235, 239, 249, 251, 253, 259, 265, 267, 273

Offset

1,1

Comments

The unique solutions are in A189482. Ufnarovski and Ahlander list these numbers on page 7 of their paper.

Interestingly, for about half the numbers n in this sequence, the unique solution is x = 2(n-2) because n-2 is prime.

References

See A003415.

Links

T. D. Noe, Table of n, a(n) for n = 1..5000

Victor Ufnarovski and Bo Ahlander, How to Differentiate a Number, J. Integer Seqs., Vol. 6, 2003.

Formula

n such that A099302(n) = 1.

Crossrefs

Cf. A003415, A099302, A189482.

Sequence in context: A285623 A213518 A214419 * A123977 A109602 A084991

Adjacent sequences: A189478 A189479 A189480 * A189482 A189483 A189484

Keyword

nonn

Author

T. D. Noe, Apr 22 2011

Status

approved