A376270 a(n) is the product of the leading digit of n and the sum of the squares of its digits.

0, 1, 8, 27, 64, 125, 216, 343, 512, 729, 1, 2, 5, 10, 17, 26, 37, 50, 65, 82, 8, 10, 16, 26, 40, 58, 80, 106, 136, 170, 27, 30, 39, 54, 75, 102, 135, 174, 219, 270, 64, 68, 80, 100, 128, 164, 208, 260, 320, 388, 125, 130, 145, 170, 205, 250, 305, 370, 445, 530, 216, 222, 240, 270, 312, 366

Offset

0,3

Links

Alois P. Heinz, Table of n, a(n) for n = 0..10000

N. Bradley Fox et al., Elated Numbers, arXiv:2409.09863 [math.NT], 2024.

Formula

a(n) = A000030(n)*A003132(n).

Maple

a:= n-> (l-> l[-1]*add(i^2, i=l))(convert(n, base, 10)):
seq(a(n), n=0..65);  # Alois P. Heinz, Sep 18 2024

Mathematica

a[n_]:=First[d=IntegerDigits[n]]Norm[d]^2; Array[a, 66, 0] (* Stefano Spezia, Sep 18 2024 *)

Prog

(PARI) a(n) = if (n, my(d=digits(n)); d[1]*norml2(d), 0);
(Python)
def a(n): return (d:=list(map(int, str(n))))[0] * sum(di*di for di in d)
print([a(n) for n in range(66)]) # Michael S. Branicky, Sep 18 2024

Crossrefs

Cf. A000030, A003132.

b-elated function: A000120 (2), A376270 (10).

Sequence in context: A254521 A351985 A352172 * A055012 A069939 A118880

Adjacent sequences: A376267 A376268 A376269 * A376271 A376272 A376273

Keyword

nonn,look,base

Author

Michel Marcus, Sep 18 2024

Status

approved