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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. 0

%I

%S 14,24,40,56,101,103,107,109,113,127,129,130,131,134,137,139,141,142,

%T 146,149,151,157,158,159,163,166,167,170,173,177,178,179,181,183,190,

%U 191,193,194,197,199,201,202,206,211,213,214,218,219,223,226,227,229

%N 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.

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

%o (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;

%K nonn,base

%O 1,1

%A _Stefan Steinerberger_, Nov 19 2005

%E Edited by _Charles R Greathouse IV_, Apr 29 2010

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Last modified November 30 22:31 EST 2021. Contains 349426 sequences. (Running on oeis4.)