A038463 Sums of 12 distinct powers of 2.

4095, 6143, 7167, 7679, 7935, 8063, 8127, 8159, 8175, 8183, 8187, 8189, 8190, 10239, 11263, 11775, 12031, 12159, 12223, 12255, 12271, 12279, 12283, 12285, 12286, 13311, 13823, 14079, 14207, 14271, 14303, 14319, 14327, 14331, 14333

Offset: 1

Author

Olivier Gérard

Keywords

• nonn
• base
• easy

Links

• Ivan Neretin, Table of n, a(n) for n = 1..10000
• Robert Baillie, Summing the curious series of Kempner and Irwin, arXiv:0806.4410 [math.CA], 2008-2015. See p. 18 for Mathematica code irwinSums.m.

Crossrefs

Base 2 interpretation of A038454.

Cf. A000079, A018900, A014311, A014312, A014313, A023688, A023689, A023690, A023691, A038461, A038462 (Hamming weight = 1, 2, ..., 11).

Programs

Mathematica

Select[Range[15000], DigitCount[#, 2, 1] == 12 &] (* Amiram Eldar, Feb 14 2022 *)

Python

from itertools import islice
def A038463_gen(): # generator of terms
    yield (n:=4095)
    while True: yield (n:=n^((a:=-n&n+1)|(a>>1)) if n&1 else ((n&~(b:=n+(a:=n&-n)))>>a.bit_length())^b)
A038463_list = list(islice(A038463_gen(),20)) # Chai Wah Wu, Mar 10 2025

Formula

Sum_{n>=1} 1/a(n) = 1.386296350824871649202152615241744383837323713474767661902780220440945591424... (calculated using Baillie's irwinSums.m, see Links). - Amiram Eldar, Feb 14 2022

Extensions

Offset changed to 1 by Ivan Neretin, Feb 28 2016