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A274620 If n^2 has an even number of digits, write n after the left half of the digits of n^2 and before the right half, otherwise if n^2 has 2t+1 digits, write n after the first t digits of n^2 and before the last t+1 digits. 1
11, 24, 39, 146, 255, 366, 479, 684, 891, 11000, 11121, 11244, 11369, 11496, 21525, 21656, 21789, 31824, 31961, 42000, 42141, 42284, 52329, 52476, 62525, 62676, 72729, 72884, 82941, 93000, 93161, 103224, 103389, 113456, 123525, 123696, 133769, 143844, 153921, 164000 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
In short, write n in the middle of n^2.
Portions of this sequence are sometimes given as puzzles.
REFERENCES
J. A. Reeds, Personal communication to N. J. A. Sloane, Jun 04 2016
LINKS
EXAMPLE
4^2 = 16 so a(4) = 1.4.6 = 146.
19^2 = 361 so a(19) = 3.19.61 = 31961.
MATHEMATICA
nterms=100; Table[FromDigits[Flatten[Insert[d=IntegerDigits[n^2], IntegerDigits[n], Floor[Length[d]/2]+1]]], {n, nterms}] (* Paolo Xausa, Nov 24 2021 *)
PROG
(Python)
def a(n):
ss = str(n*n)
t = len(ss)//2
return int(ss[:t] + str(n) + ss[t:])
print([a(n) for n in range(1, 41)]) # Michael S. Branicky, Nov 24 2021
CROSSREFS
Sequence in context: A061043 A349487 A098603 * A053061 A055820 A334597
KEYWORD
nonn,base
AUTHOR
N. J. A. Sloane, Jul 03 2016
STATUS
approved

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Last modified March 28 12:26 EDT 2024. Contains 371254 sequences. (Running on oeis4.)