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A089767 Squares which when concatenated with a 1 gives prime. 1
1, 4, 25, 49, 64, 81, 225, 400, 676, 784, 900, 1089, 1225, 1369, 1600, 1681, 2209, 2304, 3249, 3364, 4096, 5041, 6889, 7225, 7396, 8100, 8281, 8649, 9801, 10816, 11025, 11236, 12100, 12544, 12769, 13924, 15876, 16384, 17424, 19881, 21609, 21904 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Squares n such that 10*n+1 is prime. - Robert Israel, Dec 09 2017

LINKS

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

EXAMPLE

41, 4001, 6761 etc. are primes.

MAPLE

select(t -> isprime(10*t+1), map(`^`, [$1..300], 2)); # Robert Israel, Dec 09 2017

MATHEMATICA

Select[Range[150]^2, PrimeQ[10 # + 1] &] (* Michael De Vlieger, Dec 09 2017 *)

PROG

(MATLAB) A = []; count = 0; i = 1; while count < 60; s = i*i; if isprime(10*s + 1) A = [A s]; count = count + 1; end; i = i + 1; end; A

CROSSREFS

Intersection of A000290 and A024912.

Sequence in context: A231176 A199772 A245697 * A135784 A131069 A016790

Adjacent sequences:  A089764 A089765 A089766 * A089768 A089769 A089770

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, Nov 23 2003

EXTENSIONS

Corrected and extended by David Wasserman, Feb 25 2004

STATUS

approved

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Last modified October 21 08:47 EDT 2019. Contains 328292 sequences. (Running on oeis4.)