A108155 Numbers of the forms 2^n-2, 2^n-1, 2^n, 2^n+1 and 2^n+2.

-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 14, 15, 16, 17, 18, 30, 31, 32, 33, 34, 62, 63, 64, 65, 66, 126, 127, 128, 129, 130, 254, 255, 256, 257, 258, 510, 511, 512, 513, 514, 1022, 1023, 1024, 1025, 1026, 2046, 2047, 2048, 2049, 2050, 4094, 4095, 4096, 4097, 4098, 8190, 8191, 8192, 8193, 8194, 16382, 16383, 16384

Offset

1,4

Comments

This number sequence is designed for a quick test of e.g. arithmetic in binary systems.

Links

Harvey P. Dale, Table of n, a(n) for n = 1..997

Index entries for linear recurrences with constant coefficients, signature (-1,-1,-1,-1,2,2,2,2,2).

Mathematica

Flatten[Table[2^n+{-2, -1, 0, 1, 2}, {n, 0, 20}]]//Union (* Harvey P. Dale, Dec 25 2025 *)

Prog

(PARI) a(n)=if(n>12, 2^((n+7)\5)+(n+2)%5-2, n-2) \\ Charles R Greathouse IV, Jun 03 2026

Crossrefs

Union of A000918, A000225, A000079, A000051, and A052548.

Cf. A107684.

Sequence in context: A266352 A247144 A050726 * A134932 A134933 A136040

Adjacent sequences: A108152 A108153 A108154 * A108156 A108157 A108158

Keyword

sign,easy

Author

Henrik Lundquist (sploinker(AT)sploink.dk), Jun 06 2005

Status

approved