A227371 Numbers n such that prime(n) + reversal(prime(n)) is a square.

1, 10, 15, 23, 56, 89, 2279, 2581, 2683, 6329, 7845, 7942, 26074, 26146, 26290, 26651, 26871, 27080, 27960, 28687, 28898, 29396, 29539, 29824, 30038, 30333, 30404, 30472, 30955, 31025, 31097, 31168, 32076, 32143, 32429, 33502, 33564, 41608, 42011, 42148, 42696

Offset

1,2

Comments

See A059799 for the sequence of prime numbers.

Links

K. D. Bajpai, Table of n, a(n) for n = 1..340

Example

a(2)=10: prime(10)=29. Reversing digits gives 92. 29+92 = 121 = 11^2.

Maple

with(StringTools):
K := proc(n) local a, b, d, e; a :=ithprime(n): b:=parse(Reverse(convert((a), string))): d:=a+b; e:=evalf(sqrt(d)); if e=floor(e) then RETURN (n) fi:
end:
seq(K(n), n=1..100000); # K. D. Bajpai, Jul 08 2013
with(StringTools):
K:=proc()local n, a, b, c, d, e; c:=1; for n from 1 to 2000000 do; a:=ithprime(n); b:=parse(Reverse(convert((a), string))); d:=a+b; e:=evalf(sqrt(d)); if e=floor(e) then lprint(c, n); c:=c+1; fi; od; end: K(); # K. D. Bajpai, Jul 08 2013

Mathematica

Select[Range[50000], IntegerQ[Sqrt[Prime[#]+IntegerReverse[Prime[#]]]]&] (* The program uses the IntegerReverse function from Mathematica version 10 *) (* Harvey P. Dale, Jan 24 2016 *)

Crossrefs

Cf. A061231.

Sequence in context: A034961 A207637 A171444 * A057990 A272779 A173477

Adjacent sequences: A227368 A227369 A227370 * A227372 A227373 A227374

Keyword

nonn,base

Author

K. D. Bajpai, Jul 08 2013

Status

approved