A113999 - OEIS

A113999

a(n) = Sum_{ k, k|n } 10^(k-1).

1, 11, 101, 1011, 10001, 100111, 1000001, 10001011, 100000101, 1000010011, 10000000001, 100000101111, 1000000000001, 10000001000011, 100000000010101, 1000000010001011, 10000000000000001, 100000000100100111

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OFFSET

1,2

COMMENTS

A034729 to base 2. Stacking elements of the sequence gives A113998.

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..1000

FORMULA

G.f.: Sum_{n>0} x^n/(1-10*x^n).

a(n) ~ 10^(n-1). - Vaclav Kotesovec, Jun 05 2021

MATHEMATICA

A113999[n_]:= DivisorSum[n, 10^(#-1) &];

Table[A113999[n], {n, 40}] (* G. C. Greubel, Jun 26 2024 *)

PROG

(PARI) a(n)=if(n<1, 0, sumdiv(n, k, 10^(k-1)));

(Magma)

A113999:= func< n | (&+[10^(d-1): d in Divisors(n)]) >;

[A113999(n): n in [1..40]]; // G. C. Greubel, Jun 26 2024

(SageMath)

def A113999(n): return sum(10^(k-1) for k in (1..n) if (k).divides(n))

[A113999(n) for n in range(1, 41)] # G. C. Greubel, Jun 26 2024

CROSSREFS

Sums of the form Sum_{d|n} q^(d-1): A034729 (q=2), A034730 (q=3), this sequence (q=10), A339684 (q=4), A339685 (q=5), A339686 (q=6), A339687 (q=7), A339688 (q=8), A339689 (q=9).

Sequence in context: A284235 A284299 A284347 * A283062 A282959 A284142

Adjacent sequences: A113996 A113997 A113998 * A114000 A114001 A114002

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Nov 12 2005

STATUS

approved