A105303 - OEIS

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A105303

Primes formed by reverse concatenation of 5 consecutive triangular numbers.

19531891183017701711, 30032926285027752701, 4075540470401863990339621, 6570365341649806462064261, 7277172390720107163171253, 8715386736863208590585491, 190653190036189420188805188191

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..7.

EXAMPLE

a(1)=19531891183017701711 because 19531891183017701711 is the prime formed by reverse concatenation of 5 consecutive triangular numbers i.e. 1711,1770,1830,1891 and 1953.

MATHEMATICA

Module[{rtrs=Partition[Reverse[Accumulate[Range[1000]]], 5, 1]}, Sort[ Select[ FromDigits/@ (Flatten/@(IntegerDigits/@rtrs)), PrimeQ]]] (* Harvey P. Dale, Dec 12 2013 *)

CROSSREFS

Sequence in context: A221558 A114993 A175273 * A116356 A187716 A169667

Adjacent sequences: A105300 A105301 A105302 * A105304 A105305 A105306

KEYWORD

base,nonn

AUTHOR

Shyam Sunder Gupta, Apr 25 2005

STATUS

approved