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

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

Offset

1,2

Comments

a(n) = 1 iff n is a term > 0 of A007088. - Bernard Schott, Mar 24 2022

Links

Table of n, a(n) for n=1..63.

Formula

a(n) = A051801(n)^2.

a(10*n) = a(n). - Bernard Schott, Mar 24 2022

Mathematica

a[n_] := (Times @@ Select[IntegerDigits[n], # > 1 &])^2; Array[a, 65] (* Amiram Eldar, Mar 22 2022 *)

Prog

(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')
print([a(n) for n in range(1, 64)]) # Michael S. Branicky, Mar 22 2022
(Python)
from math import prod
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

Crossrefs

Cf. A007088, A051801, A352172.

Sequence in context: A002015 A257587 A257588 * A303269 A003132 A062331

Adjacent sequences: A352595 A352596 A352597 * A352599 A352600 A352601

Keyword

nonn,base

Author

Michel Marcus, Mar 22 2022

Status

approved