A111743 Numbers n such that the largest prime factor p of n is also the largest prime factor of n.p, where the dot means concatenation.

14, 24, 40, 56, 101, 103, 107, 109, 113, 127, 129, 130, 131, 134, 137, 139, 141, 142, 146, 149, 151, 157, 158, 159, 163, 166, 167, 170, 173, 177, 178, 179, 181, 183, 190, 191, 193, 194, 197, 199, 201, 202, 206, 211, 213, 214, 218, 219, 223, 226, 227, 229

Offset

1,1

Links

Table of n, a(n) for n=1..52.

Example

249 = 3*83; 24983 = 7*43*83; both numbers have the same largest prime factor, so 249 is in the sequence.

Prog

(MuPAD) for n from 2 to 500 do A := ifactor(n); b := A[nops(A)-1]; zi := trunc(log(10, b)+1); nn := n*10^zi+b; B := ifactor(nn); if A[nops(A)-1] = B[nops(B)-1] then print(n, b); end_if; end_for;

Crossrefs

Sequence in context: A111455 A171124 A046290 * A164399 A164404 A211323

Adjacent sequences: A111740 A111741 A111742 * A111744 A111745 A111746

Keyword

nonn,base

Author

Stefan Steinerberger, Nov 19 2005

Extensions

Edited by Charles R Greathouse IV, Apr 29 2010

Status

approved