login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A331465 a(n) begins the first run of exactly n consecutive binary Smith numbers (A278909). 1
15, 1390, 1369, 11763, 47802, 1529690, 4628217, 1544053, 804607562, 4747704789 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(11) > 5*10^10.

LINKS

Table of n, a(n) for n=1..10.

EXAMPLE

a(2) = 1390 since 1390 and 1391 are binary Smith numbers.

a(3) = 1369 since 1369, 1370, and 1371 are binary Smith numbers.

MATHEMATICA

binWt[n_] := Total@IntegerDigits[n, 2]; binSmithQ[n_] := CompositeQ[n] && Plus @@ (Last@# * binWt[ First@# ] & /@ FactorInteger[n]) == binWt[n]; n = 1; count = 0; max = 6; seq = Table[0, {max}]; While[count < max, n1 = n; If[binSmithQ[n], While[binSmithQ[++n1]]; d = n1 - n; If[d <= max && seq[[d]] == 0, count++; seq[[d]] = n]]; n = n1 + 1]; seq

CROSSREFS

Cf. A278909, A329942, A331464.

Sequence in context: A183550 A071972 A206376 * A223058 A200994 A338634

Adjacent sequences:  A331462 A331463 A331464 * A331466 A331467 A331468

KEYWORD

nonn,base,more

AUTHOR

Amiram Eldar, Jan 17 2020

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 July 29 23:30 EDT 2021. Contains 346346 sequences. (Running on oeis4.)