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A265181 Prime numbers resulting from the concatenation of at least two copies of a cubic number followed by a trailing "1." 1
881, 27271, 7297291, 133113311, 337533751, 19683196831, 42875428751, 68921689211, 1038231038231, 1574641574641, 2053792053791, 2744274427441, 4218754218751, 6859685968591, 7290007290001, 7297297297291, 106120810612081, 224809122480911, 274400027440001, 280322128032211, 317652331765231, 500021150002111, 812060181206011, 1251251251251251, 1757617576175761, 1968319683196831, 5931959319593191 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Subsequence of A030430 (primes of the form 10n+1). - Michel Marcus, Dec 04 2015

If m is a term then (m-1)/10 is divisible by a cube (A000578) and the resulting quotient, different from 1, is in A076289. - Michel Marcus, Dec 05 2015

Without the "repeated at least twice" constraint, A168147 would be a subsequence. - Michel Marcus, Dec 05 2015

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

8 = 2^3; 881 is prime.

27 = 3^3; 27271 is prime.

MAPLE

N:= 20: # to get all terms with at most N digits

M:= floor((N-1)/2):

res:= {}:

for s from 1 to floor(10^(M/3)) do

   x:= s^3;

   m:= 1+ilog10(x);

   for k from 2 to floor((N-1)/m) do

     p:= x*add(10^(1+m*i), i=0..k-1)+1;

     if isprime(p) then res:= res union {p} fi;

   od

od:

sort(convert(res, list)); # Robert Israel, Jan 13 2016

MATHEMATICA

Take[Sort@ Flatten[Select[#, PrimeQ] & /@ Table[FromDigits@ Append[Flatten@ IntegerDigits@ Table[n^3, {#}], 1] & /@ Range[2, 20], {n, 1, 300}] /. {} -> Nothing], 27] (* Michael De Vlieger, Jan 05 2016 *)

CROSSREFS

Cf. A000578, A030430, A066592, A076289, A168147 , A232066.

Sequence in context: A024393 A006052 A105976 * A137064 A092675 A135127

Adjacent sequences:  A265178 A265179 A265180 * A265182 A265183 A265184

KEYWORD

nonn,base

AUTHOR

Thomas S. Pedigo, Dec 03 2015

STATUS

approved

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Last modified July 20 22:51 EDT 2017. Contains 289629 sequences.