A239992 Primes formed by concatenating a square number S with S+1, where S+1 is a prime number.

3637, 576577, 2433624337, 3240032401, 4410044101, 6969669697, 352836352837, 404496404497, 746496746497, 16641001664101, 17424001742401, 20050562005057, 20736002073601, 24523562452357, 26049962604997, 28022762802277, 34596003459601, 35494563549457, 42600964260097

Offset

1,1

Comments

It is observed that each term in the sequence ends either with digit 1 or 7.

Links

K. D. Bajpai, Table of n, a(n) for n = 1..1060

Example

3637 is a prime formed by concatenaing 36 with 37 where 36= 6^2 and (36+1)= 37 is a prime.
576577 is a prime formed by concatenaing 576 with 577 where 576= 24^2 and (576+1)= 577 is a prime.

Maple

with(StringTools):KD := proc() local a, b, s; s:=n*n; b:=s+1; if isprime(b) then a:= parse(cat(s, b )); if isprime(a) then RETURN (a); fi; fi; end: seq(KD(), n=1..5000);

Crossrefs

Cf. A000040, A030458.

Sequence in context: A206836 A206898 A207288 * A253498 A253491 A253452

Adjacent sequences: A239989 A239990 A239991 * A239993 A239994 A239995

Keyword

nonn,base

Author

K. D. Bajpai, Mar 30 2014

Status

approved