A099551 Odd part of n modulo 10. Final digit of A000265(n).

1, 1, 3, 1, 5, 3, 7, 1, 9, 5, 1, 3, 3, 7, 5, 1, 7, 9, 9, 5, 1, 1, 3, 3, 5, 3, 7, 7, 9, 5, 1, 1, 3, 7, 5, 9, 7, 9, 9, 5, 1, 1, 3, 1, 5, 3, 7, 3, 9, 5, 1, 3, 3, 7, 5, 7, 7, 9, 9, 5, 1, 1, 3, 1, 5, 3, 7, 7, 9, 5, 1, 9, 3, 7, 5, 9, 7, 9, 9, 5, 1, 1, 3, 1, 5, 3, 7, 1, 9, 5, 1, 3, 3, 7, 5, 3, 7, 9, 9, 5, 1, 1

Offset

1,3

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Formula

a(n) = A010879(A000265(n)).

G.f. g(x) satisfies: g(x) = g(x^2) + (x + 3*x^3 + 5*x^5 + 7*x^7 + 9*x^9)/(1-x^10). - Robert Israel, Aug 10 2018

Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = 5. - Amiram Eldar, Aug 29 2024

Maple

f:= n -> n/2^padic:-ordp(n, 2) mod 10:
map(f, [$1..200]); # Robert Israel, Aug 10 2018

Mathematica

Mod[Table[Max[Select[Divisors[n], OddQ]], {n, 110}], 10] (* Harvey P. Dale, Jun 22 2017 *)
a[n_] := Mod[n / 2^IntegerExponent[n, 2], 10]; Array[a, 100] (* Amiram Eldar, Aug 29 2024 *)

Prog

(PARI) a(n)=(n>>valuation(n, 2))%10 \\ Charles R Greathouse IV, Dec 28 2012

Crossrefs

Cf. A000265, A010879.

Cf. A099544, A099545, A099546, A099547, A099548, A099549, A099550.

Sequence in context: A081431 A053641 A161825 * A211206 A330717 A036233

Adjacent sequences: A099548 A099549 A099550 * A099552 A099553 A099554

Keyword

nonn,base,easy

Author

Ralf Stephan, Oct 23 2004

Status

approved