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A192689
Squares for which no final group of decimal digits less than the total forms a square.
2
16, 25, 36, 196, 256, 576, 676, 1156, 1296, 4096, 4356, 5476, 5776, 7056, 7396, 12996, 13456, 15376, 15876, 17956, 18496, 26896, 27556, 30276, 30976, 33856, 34596, 45796, 46656, 50176, 51076, 54756, 55696, 69696, 70756, 75076, 76176, 80656, 81796, 98596
OFFSET
1,1
COMMENTS
25 is the only member of sequence that does not end in 6. Proof: All squares end in 0, 1, 4, 5, 6, or 9. 0, 1, 4, 9 can be ruled out because they're squares themselves. This leaves only 5 and 6. 25 qualifies. However, all squares that end in 5 end in 25, making it impossible for a square number ending in 5 with more than 2 digits to qualify, leaving only 6 as a valid final digit for all members of this sequence with 3 or more digits.
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
EXAMPLE
1936 is not a member of this sequence because 36 is a perfect square.
MATHEMATICA
fdsQ[n_]:=NoneTrue[Table[Mod[n, 10^d], {d, IntegerLength[n]-1}], IntegerQ[Sqrt[#]]&]; Select[Range[4, 350]^2, fdsQ] (* Harvey P. Dale, Oct 16 2024 *)
CROSSREFS
Cf. A242077.
Sequence in context: A264604 A348235 A218439 * A002644 A118489 A110922
KEYWORD
nonn,base,changed
AUTHOR
J. Lowell, Jul 07 2011
EXTENSIONS
a(11)-a(40) from Charles R Greathouse IV, Jul 08 2011
STATUS
approved