This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A371281 #31 Mar 22 2024 20:08:21 %S A371281 0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,2,4,6,8,0,2,4,6,8,0,3,6,9, %T A371281 2,5,8,1,4,7,0,4,8,2,6,0,4,8,2,6,0,5,0,5,0,5,0,5,0,5,0,6,2,8,4,0,6,2, %U A371281 8,4,0,7,4,1,8,5,2,9,6,3,0,8,6,4,2,0,8,6,4,2,0,9,8 %N A371281 Last digit of the product of decimal digits of n. %C A371281 n=0 is taken as one 0 digit so that its product of digits is A007954(0) = 0. %H A371281 Alois P. Heinz, <a href="/A371281/b371281.txt">Table of n, a(n) for n = 0..10000</a> %F A371281 a(n) = A007954(n) mod 10. %F A371281 a(n) = A010879(A007954(n)). %e A371281 n = 15: a(15) = 1*5 mod 10 = 5. %e A371281 n = 26: a(26) = 2*6 mod 10 = 2. %p A371281 a:= n-> `if`(n<10, n, irem(n, 10, 'q')*a(q) mod 10): %p A371281 seq(a(n), n=0..92); # _Alois P. Heinz_, Mar 17 2024 %t A371281 a[n_] := Mod[Times @@ IntegerDigits[n], 10]; Array[a, 100, 0] (* _Amiram Eldar_, Mar 17 2024 *) %o A371281 (Python) %o A371281 from math import prod %o A371281 def a(n): return prod(map(int, str(n)))%10 %o A371281 print([a(n) for n in range(93)]) # _Michael S. Branicky_, Mar 17 2024 %o A371281 (PARI) a(n) = if (n==0, 0, vecprod(digits(n)) % 10); \\ _Michel Marcus_, Mar 17 2024 %Y A371281 Cf. A007954, A010879, A036987 (similar for 2 instead of 10), A053837. %K A371281 nonn,base %O A371281 0,3 %A A371281 _Ctibor O. Zizka_, Mar 17 2024