login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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. - Moshe Levin, 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: A049054 A135476 A255310 * A275522 A110975 A190120

Adjacent sequences:  A051214 A051215 A051216 * A051218 A051219 A051220

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified October 22 02:06 EDT 2017. Contains 293756 sequences.