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A067757
Numbers k whose last digit is the k-th digit of sqrt(2).
3
15, 18, 20, 21, 39, 45, 47, 49, 67, 87, 92, 117, 122, 126, 147, 149, 162, 165, 170, 179, 192, 197, 205, 235, 237, 264, 272, 274, 275, 279, 282, 286, 289, 292, 297, 305, 313, 318, 335, 340, 344, 345, 356, 381, 384, 394, 403, 409, 418, 433, 446, 449, 471, 476
OFFSET
1,1
COMMENTS
The k-th digit of sqrt(2) is calculated starting after the decimal point. - Harvey P. Dale, Jan 29 2023
EXAMPLE
Let d(n) be the n-th digit of sqrt(2)=1.4142... so d(1)=4, d(2)=1 etc. d(122)=2 and 2 is the last digit of 122 hence 122 is in the sequence.
MATHEMATICA
Module[{nn=500, sq2}, sq2=RealDigits[Sqrt[2], 10, nn][[1]]; Select[Range[nn-1], Mod[ #, 10] == sq2[[#+1]]&]] (* Harvey P. Dale, Jan 29 2023 *)
PROG
(Python 3.8+)
from math import isqrt
A067757_list = [i for i, d in enumerate(str(isqrt(2*100**100000))) if i % 10 == int(d)] # Chai Wah Wu, Jul 08 2021
CROSSREFS
KEYWORD
easy,nonn,base
AUTHOR
Benoit Cloitre, Mar 07 2002
STATUS
approved