login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A202274 Positive integers m in increasing order determined by these rules: a(1) = 1, for n>=1,  if m is in the sequence then also are numbers h such that sigma(h) = 4m-1. 1
1, 2, 4, 8, 16, 25, 32, 64, 128, 256, 512, 1024, 2048, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 131072, 262144, 524288, 1048576, 2097152, 4194304, 8388608, 16777216, 33554432, 67108864, 134217728, 268435456, 536870912, 1073741824, 2147483648, 4294967296 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

If 31 is only number h of form 2^k-1 for any k>=1 such that sigma(x) = h has solution for more than one value of x then a(n) is union number 25 with A000079 (powers of 2).

LINKS

Table of n, a(n) for n=1..36.

EXAMPLE

m=1, 4m-1=3, sigma(h)=3 for h=2; number 2 is in sequence.

m=2, 4m-1=7, sigma(h)=7 for h=4; number 4 is in sequence.

m=4, 4m-1=15, sigma(h)=15 for h=8; number 8 is in sequence.

m=8, 4m-1=31, sigma(h)=31 for h=16 and 25; numbers 16 and 25 are in sequence.

CROSSREFS

Cf. A000203, A002191, A202273.

Sequence in context: A119311 A305183 A112992 * A070789 A302588 A319385

Adjacent sequences:  A202271 A202272 A202273 * A202275 A202276 A202277

KEYWORD

nonn

AUTHOR

Jaroslav Krizek, Dec 25 2011

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 17 08:36 EDT 2019. Contains 328107 sequences. (Running on oeis4.)