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A062672 Composite and every divisor (except 1) contains the digit 5. 18

%I #15 Jan 22 2023 15:45:29

%S 25,125,265,295,625,755,785,1255,1285,1325,1475,1765,1795,2285,2515,

%T 2545,2605,2615,2705,2735,2785,2815,2845,2855,2885,2935,2965,2995,

%U 3125,3265,3295,3755,3775,3785,3925,4265,4285,4295,4765,5255,5755,5765,6275

%N Composite and every divisor (except 1) contains the digit 5.

%H Amiram Eldar, <a href="/A062672/b062672.txt">Table of n, a(n) for n = 1..10000</a>

%e 25 has divisors 1, 5 and 25, all of which contain the digit 5.

%t fQ[n_, dgt_] := Union[ MemberQ[#, dgt] & /@ IntegerDigits@ Rest@ Divisors@ n][[1]]; Select[ Range[2, 6300], !PrimeQ[#] && fQ[#, 5] &] (* _Robert G. Wilson v_, Jun 11 2014 *)

%t Select[Range[6300],CompositeQ[#]&&AllTrue[Rest[Divisors[#]],DigitCount[ #,10,5]> 0&]&] (* _Harvey P. Dale_, Jan 22 2023 *)

%Y Cf. A062653, A062664, A062667, A062668, A062669, A062670, A062671, A062673, A062674, A062675, A062676, A062677, A062678, A062679, A062680.

%K base,easy,nonn

%O 1,1

%A _Erich Friedman_, Jul 04 2001

%E Offset corrected by _Amiram Eldar_, Nov 07 2019

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Last modified May 14 23:22 EDT 2024. Contains 372535 sequences. (Running on oeis4.)