login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A253598 a(n) = least Lucas-Carmichael number which is divisible by b(n), where {b(n)} (A255602) is the list of all numbers which could be a divisor of a Lucas-Carmichael number. 3
399, 399, 935, 399, 935, 2015, 935, 399, 399, 4991, 51359, 2015, 8855, 1584599, 9486399, 20705, 5719, 18095, 2915, 935, 399, 46079, 162687, 2015, 22847, 46079, 16719263, 8855, 12719, 7055, 935, 80189, 189099039, 104663, 20705, 482143, 196559, 60059, 30073928079, 90287, 8855, 31535 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(271) <= 3394263983671190271. - Daniel Suteu, Sep 11 2022

LINKS

Daniel Suteu, Table of n, a(n) for n = 1..270 (first 95 terms from Tim Johannes Ohrtmann, terms 96..154 from Robert G. Wilson v)

EXAMPLE

a(12) = 8855 because this is the least Lucas-Carmichael number which is divisible by A255602(12) = 35.

MATHEMATICA

LucasCarmichaelQ[n_] := Block[{fi = FactorInteger@ n}, ! PrimeQ@ n && Times @@ (Last@# & /@ fi) == 1 && Plus @@ Mod[n + 1, 1 + First@# & /@ fi] == 0]; LucasCarmichaelQ[1] = False; fQ[n_] := Block[{fi = FactorInteger@ n}, ffi = First@# & /@ fi; Times @@ (Last@# & /@ fi) == 1 && Min@ Flatten@ Table[Mod[1 + ffi, i], {i, ffi}] > 0]; fQ[1] = True; fQ[2] = False; lcdv = Select[ Range@ 3204, fQ]; f[n_] := Block[{k = lcdv[[n]]}, d = 2k; While[ !LucasCarmichaelQ@ k, k += d]; k]; Array[f, 95] (* Robert G. Wilson v, Feb 11 2015 *)

CROSSREFS

Cf. A006972, A253597, A255602.

Sequence in context: A235569 A261768 A274446 * A046013 A352360 A176911

Adjacent sequences:  A253595 A253596 A253597 * A253599 A253600 A253601

KEYWORD

nonn

AUTHOR

Tim Johannes Ohrtmann, Jan 05 2015

EXTENSIONS

a(96) from Charles R Greathouse IV, Feb 12 2015

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 6 20:00 EDT 2022. Contains 357270 sequences. (Running on oeis4.)