OFFSET
1,2
COMMENTS
Of this sequence's first 10000 terms, only nine have an even number of digits; see A354256.
LINKS
Jon E. Schoenfield, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Reinhard Zumkeller)
EXAMPLE
144 = 12 * 12 is a term because 441 = 21 * 21.
MATHEMATICA
Select[Range[1100]^2, Mod[#, 10]!=0&&IntegerQ[Sqrt[FromDigits[Reverse[ IntegerDigits[ #]]]]]&] (* Harvey P. Dale, Oct 28 2013 *)
PROG
(Haskell)
a033294 n = a033294_list !! (n-1)
a033294_list = filter chi a000290_list where
chi m = m `mod` 10 > 0 && head ds `elem` [1, 4, 5, 6, 9] &&
a010052 (foldl (\v d -> 10 * v + d) 0 ds) == 1 where
ds = unfoldr
(\x -> if x == 0 then Nothing else Just $ swap $ divMod x 10) m
-- Reinhard Zumkeller, Jan 19 2012
(Python)
from math import isqrt
from itertools import count, islice
def sqr(n): return isqrt(n)**2 == n
def agen():
yield from (k*k for k in count(1) if k%10 and sqr(int(str(k*k)[::-1])))
print(list(islice(agen(), 36))) # Michael S. Branicky, May 21 2022
CROSSREFS
KEYWORD
base,nonn
AUTHOR
EXTENSIONS
More terms from Erich Friedman
Initial 0 removed and offset changed by Reinhard Zumkeller, Jan 19 2012
STATUS
approved