A273125 Numbers n for which 3*n is an isolated deficient number.

117, 667, 737, 917, 997, 1003, 1083, 1237, 1283, 1503, 1577, 1723, 2077, 2357, 2403, 2637, 2963, 3117, 3197, 3243, 3803, 4583, 4737, 4923, 5717, 5997, 6043, 6197, 6277, 6283, 6517, 6717, 6827, 7163, 7397, 7663, 7723, 7817, 8017, 8563

Offset

1,1

Comments

Numbers n for which 3n-2, 3n, and 3n+2 are isolated deficient numbers.

The vast majority of terms (probably around 98.6%) end in either 7 or 3, with a(1) = 117 and a(6) = 1003 being the first instances of each. The first instances of the other digits are: a(91) = 19595, a(187) = 39989, a(213) = 46251. Of the first 151725 terms (those less than 10^8), 74769 end in 7, 670 end in 1, 701 end in 5, 685 end in 9, and 74900 end in 3.

Links

Timothy L. Tiffin, Table of n, a(n) for n = 1..151725 [terms < (1/3)*10^8]

Example

a(1) = 117 since the following three integers are isolated deficient numbers:
   3*117 - 2 = 349 = A274849(26) = A276049(17) = A133855(16).
   3*117     = 351 = A274849(27).
   3*117 + 2 = 353 = A274849(28) = A276049(18) = A133855(17).

Crossrefs

Cf. A133855, A274849, A276049.

Sequence in context: A255022 A217798 A252853 * A327599 A326064 A233376

Adjacent sequences: A273122 A273123 A273124 * A273126 A273127 A273128

Keyword

nonn

Author

Timothy L. Tiffin, Aug 28 2016

Status

approved