login
A027720
Palindromes of form k^2 + 1.
5
1, 2, 5, 101, 626, 10001, 1000001, 1040401, 2217122, 5053505, 100000001, 101808101, 10000000001, 10182828101, 10408080401, 28053235082, 1000000000001, 1000400040001, 1018262628101, 7534662664357, 100000000000001, 100018000810001, 101826464628101
OFFSET
1,2
COMMENTS
10^(2*m) + 1 for m >= 0 are terms. - Chai Wah Wu, May 25 2017
FORMULA
a(n) = A027719(n)^2 + 1. - Giovanni Resta, Aug 29 2018
MATHEMATICA
palQ[n_] := Block[{d = IntegerDigits[n]}, d == Reverse[d]]; Select[Range[0, 10^5]^2 + 1, palQ] (* Giovanni Resta, Aug 29 2018 *)
CROSSREFS
KEYWORD
nonn,base
EXTENSIONS
More terms from Giovanni Resta, Aug 28 2018
STATUS
approved