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 A177054 Numbers k such that each of the decimal digits is a quadratic residue modulo k. 0
 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 19, 23, 33, 37, 39, 40, 41, 44, 46, 47, 49, 55, 59, 69, 74, 82, 89, 90, 91, 94, 95, 98, 99, 100, 101, 104, 106, 109, 110, 111, 114, 119, 131, 140, 141, 142, 143, 144, 145, 146, 149, 151, 155, 158, 167, 171, 174, 177, 184, 188, 190, 191, 193, 194, 197, 199, 217 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS EXAMPLE 673 is in the sequence because L(6/673) = L(7/673) = L(3/673) = 1 where L(a/b) is the Legendre symbol of a and b, which is defined to be 1 if a is a quadratic   residue (mod b) and -1 if a is a quadratic non-residue (mod b). MAPLE isA177054 := proc(n) local d; for d in convert(n, base, 10) do if numtheory[quadres](d, n) <> 1 then return false; end if; end do; return true; end proc: for n from 1 to 140 do if isA177054(n) then printf("%d, ", n) ; end if ; end do: # R. J. Mathar, Dec 12 2010 CROSSREFS Sequence in context: A229991 A178156 A334294 * A247760 A247750 A051534 Adjacent sequences:  A177051 A177052 A177053 * A177055 A177056 A177057 KEYWORD nonn,base,less AUTHOR Michel Lagneau, Dec 09 2010 STATUS approved

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Last modified January 17 16:45 EST 2021. Contains 340247 sequences. (Running on oeis4.)