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A068676 Primes formed by the concatenation 1, n, n^2, n, 1. 1
12421, 13931, 163661, 186481, 115225151, 121441211, 122484221, 124576241, 131961311, 1502500501, 1512601511, 1603600601, 1674489671, 1735329731, 1806400801, 1816561811, 1100100001001, 1101102011011, 1104108161041 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

EXAMPLE

163661 is a prime which is the concatenation of 1, 6, 36, 6 and 1.

MATHEMATICA

d[n_]:=IntegerDigits[n]; Select[Table[FromDigits[Join[{1}, d[n], d[n^2], d[n], {1}]], {n, 110}], PrimeQ] (* Jayanta Basu, May 20 2013 *)

Select[Table[FromDigits[Flatten[IntegerDigits/@{1, n, n^2, n, 1}]], {n, 200}], PrimeQ] (* Harvey P. Dale, May 25 2019 *)

CROSSREFS

Sequence in context: A224120 A233964 A156116 * A252613 A221016 A237901

Adjacent sequences:  A068673 A068674 A068675 * A068677 A068678 A068679

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, Mar 02 2002

EXTENSIONS

More terms from Sascha Kurz, Mar 27 2002

STATUS

approved

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Last modified January 20 08:07 EST 2020. Contains 331081 sequences. (Running on oeis4.)