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A167217 Primes such that their reversal + 1 is a square. 3
3, 53, 827, 3671, 5507, 8423, 8693, 30293, 42083, 42281, 42299, 53639, 57203, 59921, 80819, 326681, 345473, 345887, 348191, 361637, 387449, 420803, 422243, 510299, 511019, 551339, 574181, 590813, 593171, 804653, 806363, 808991, 829601, 863729, 867131, 888011 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Robert Israel and K. D. Bajpai, Table of n, a(n) for n = 1..10000 (first 506 entries from Bajpai)

EXAMPLE

53 is prime and 35 + 1 = 36 = 6^2.

827 is in the sequence because it is prime.  Also, reversal(827) + 1 = 728 + 1 = 729 = 27^2. - K. D. Bajpai, Jul 03 2014

MAPLE

Nd:= 4: # to get all entries with up to 2*Nd digits

revdigs:= proc(x) local F, n, i;

F:= convert(x, base, 10);

n:= nops(F);

add(10^(n-i)*F[i], i=1..n);

end:

Sq:= remove(t -> (t mod 10 = 1), {seq(i^2, i=1..10^Nd-1)}):

A:=map(proc(s) local r; r:= revdigs(s-1); if isprime(r) then r else NULL fi end proc, Sq); # Robert Israel, Jul 03 2014

MATHEMATICA

Select[Prime[Range[10^5]], IntegerQ[Sqrt[FromDigits[Reverse[IntegerDigits[#]]] + 1]] &] (* K. D. Bajpai, Jul 03 2014 *)

CROSSREFS

Sequence in context: A173802 A001279 A092447 * A203561 A333563 A273802

Adjacent sequences:  A167214 A167215 A167216 * A167218 A167219 A167220

KEYWORD

base,nonn

AUTHOR

Claudio Meller, Oct 30 2009

EXTENSIONS

More terms from K. D. Bajpai, Jul 03 2014

STATUS

approved

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Last modified July 30 03:31 EDT 2021. Contains 346347 sequences. (Running on oeis4.)