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A359841 Integers Xd which are divisible by X, where d is the last decimal digit.

%I A359841 #36 Jan 20 2023 15:39:11
%S A359841 10,11,12,13,14,15,16,17,18,19,20,22,24,26,28,30,33,36,39,40,44,48,50,
%T A359841 55,60,66,70,77,80,88,90,99,100,110,120,130,140,150,160,170,180,190,
%U A359841 200,210,220,230,240,250,260,270,280,290,300,310,320,330,340,350,360,370,380,390,400,410,420
%N A359841 Integers Xd which are divisible by X, where d is the last decimal digit.
%C A359841 Integers k such that k is divisible by A059995(k).
%C A359841 This sequence consists of {the thirty-two 2-digit terms of A034837 (from 10 up to 99)} Union {the positive multiples of 10 (A008592\{0})}.
%H A359841 N. N. Chentzov, D. O. Shklarsky, and I. M. Yaglom, <a href="https://archive.org/details/ussr_olympiad_problem_book/page/n106/mode/1up">The USSR Olympiad Problem Book, Selected Problems and Theorems of Elementary Mathematics</a>, problem 15, pp. 11 and 102, Dover publications, Inc., New York, 1993.
%H A359841 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).
%t A359841 Select[Range[10, 500], Divisible[#, Floor[#/10]] &] (* _Amiram Eldar_, Jan 15 2023 *)
%o A359841 (Python)
%o A359841 def ok(n): return n > 9 and n%(n//10) == 0
%o A359841 print([k for k in range(421) if ok(k)]) # _Michael S. Branicky_, Jan 15 2023
%o A359841 (Python)
%o A359841 def A359841(n): return (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 24, 26, 28, 30, 33, 36, 39, 40, 44, 48, 50, 55, 60, 66, 70, 77, 80, 88, 90, 99)[n-1] if n <= 32 else (n-23)*10 # _Chai Wah Wu_, Jan 20 2023
%o A359841 (PARI) isok(k) = (k>9) && (k % (k \ 10) == 0); \\ _Michel Marcus_, Jan 20 2023
%Y A359841 Cf. A034837, A059995, A178157, A292683 (similar but with dX).
%Y A359841 Subsequence: A008592\{0}.
%K A359841 nonn,base,easy
%O A359841 1,1
%A A359841 _Bernard Schott_, Jan 15 2023