The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History forA083888

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Showing entries 1-10 |older changes

A083888

Number of divisors of n with largest digit = 1 (base 10).
(history; published version)

#20byMichel Marcusat Thu Jan 04 01:43:09 EST 2024

STATUS

reviewed

approved

#19byJoerg Arndtat Thu Jan 04 01:04:15 EST 2024

STATUS

proposed

reviewed

#18byAmiram Eldarat Thu Jan 04 00:30:18 EST 2024

STATUS

editing

proposed

#17byAmiram Eldarat Thu Jan 04 00:07:10 EST 2024

FORMULA

Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = Sum_{k>=1} 1/A007088(k) = 1.23840561530559480971.... -Amiram Eldar,Jan 04 2024

CROSSREFS

Cf.A054055,A000005,A007088,A083889,A083890,A083891,A083892,A083893,A083894,A083895,A083896.

STATUS

approved

editing

#16bySusanna Cuylerat Sun Oct 06 18:22:25 EDT 2019

STATUS

proposed

approved

#15byMichael De Vliegerat Sun Oct 06 17:54:29 EDT 2019

STATUS

editing

proposed

#14byMichael De Vliegerat Sun Oct 06 17:54:27 EDT 2019

MATHEMATICA

With[{k = 1}, Array[DivisorSum[#, 1 &, And[#[[k]] > 0, Total@ #[[k + 1;; 9]] == 0] &@ DigitCount[#] &] &, 105]] (*Michael De Vlieger,Oct 06 2019 *)

STATUS

proposed

editing

#13byMichel Marcusat Sun Oct 06 17:23:01 EDT 2019

STATUS

editing

proposed

#12byMichel Marcusat Sun Oct 06 17:22:57 EDT 2019

COMMENTS

a(n) =A000005(n) -A083889(n) -A083890(n) -A083891(n) -A083892(n) -A083893(n) -A083894(n) -A083895(n) -A083896(n).

FORMULA

a(n) =A000005(n) -A083889(n) -A083890(n) -A083891(n) -A083892(n) -A083893(n) -A083894(n) -A083895(n) -A083896(n).

STATUS

proposed

editing

#11byMichel Marcusat Sun Oct 06 17:20:38 EDT 2019

STATUS

editing

proposed