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A352598 a(n) is the product of the squares of the nonzero digits of n.

%I A352598 #21 Sep 18 2024 05:43:39
%S A352598 1,4,9,16,25,36,49,64,81,1,1,4,9,16,25,36,49,64,81,4,4,16,36,64,100,
%T A352598 144,196,256,324,9,9,36,81,144,225,324,441,576,729,16,16,64,144,256,
%U A352598 400,576,784,1024,1296,25,25,100,225,400,625,900,1225,1600,2025,36,36,144,324
%N A352598 a(n) is the product of the squares of the nonzero digits of n.
%C A352598 a(n) = 1 iff n is a term > 0 of A007088. - _Bernard Schott_, Mar 24 2022
%F A352598 a(n) = A051801(n)^2.
%F A352598 a(10*n) = a(n). - _Bernard Schott_, Mar 24 2022
%t A352598 a[n_] := (Times @@ Select[IntegerDigits[n], # > 1 &])^2; Array[a, 65] (* _Amiram Eldar_, Mar 22 2022 *)
%o A352598 (PARI) a(n) = vecprod(apply(x->x^2, select(x->(x>1), digits(n))));
%o A352598 (Python)
%o A352598 from math import prod
%o A352598 def a(n): return prod(int(d)**2 for d in str(n) if d != '0')
%o A352598 print([a(n) for n in range(1, 64)]) # _Michael S. Branicky_, Mar 22 2022
%o A352598 (Python)
%o A352598 from math import prod
%o A352598 def A352598(n): return prod(map(lambda x:(0, 1, 4, 9, 16, 25, 36, 49, 64, 81)[int(x)],filter(lambda x:x>'1',str(n)))) # _Chai Wah Wu_, Sep 17 2024
%Y A352598 Cf. A007088, A051801, A352172.
%K A352598 nonn,base
%O A352598 1,2
%A A352598 _Michel Marcus_, Mar 22 2022