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 A051217 Nonnegative numbers of the form 6^x - y^2. 5
 0, 1, 2, 5, 6, 11, 20, 27, 32, 35, 36, 47, 71, 72, 95, 116, 135, 140, 152, 167, 180, 191, 200, 207, 212, 215, 216, 272, 335, 380, 396, 431, 455, 512, 551, 567, 620, 671, 720, 767, 812, 855, 860, 887, 896, 935, 972, 1007, 1040, 1052, 1071, 1100, 1127, 1152 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS No integers congruent to {3,4,8,9} mod 10. - Zak Seidov, Nov 14 2011. If n is not in this sequence, then A200440 gives the least modulus which proves that there cannot be a solution to n=6^x-y^2. - M. F. Hasler, Nov 18 2011 LINKS Hugo Pfoertner, Table of n, a(n) for n = 1..513 MATHEMATICA max = 10^5; Clear[f]; f[m_] := f[m] = Select[Table[6^x - y^2, {x, 0, m}, {y, 0, Ceiling[6^(x/2)]}] // Flatten // Union, 0 <= # <= max &]; f[1]; f[m = 2]; While[f[m] != f[m - 1], m++]; Print["m = ", m]; A051217 = f[m] (* Jean-François Alcover, May 13 2017 *) PROG (PARI) is_A051217(n) = !A200440(n)  \\ - M. F. Hasler, Nov 18 2011 CROSSREFS Cf. A201122. Sequence in context: A336902 A135476 A255310 * A275522 A110975 A190120 Adjacent sequences:  A051214 A051215 A051216 * A051218 A051219 A051220 KEYWORD nonn AUTHOR STATUS approved

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Last modified September 16 23:53 EDT 2021. Contains 347477 sequences. (Running on oeis4.)