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A352598
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a(n) is the product of the squares of the nonzero digits of n.
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2
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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, 144, 196, 256, 324, 9, 9, 36, 81, 144, 225, 324, 441, 576, 729, 16, 16, 64, 144, 256, 400, 576, 784, 1024, 1296, 25, 25, 100, 225, 400, 625, 900, 1225, 1600, 2025, 36, 36, 144, 324
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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MATHEMATICA
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a[n_] := (Times @@ Select[IntegerDigits[n], # > 1 &])^2; Array[a, 65] (* Amiram Eldar, Mar 22 2022 *)
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PROG
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(PARI) a(n) = vecprod(apply(x->x^2, select(x->(x>1), digits(n))));
(Python)
from math import prod
def a(n): return prod(int(d)**2 for d in str(n) if d != '0')
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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