A091284 Exponent of 2 in -1+prime[n]^s, if s is an exponent of form 16k-8. Except a(1)=0, a(n)=1+A091283(n).

0, 5, 5, 6, 5, 5, 7, 5, 6, 5, 8, 5, 6, 5, 7, 5, 5, 5, 5, 6, 6, 7, 5, 6, 8, 5, 6, 5, 5, 7, 10, 5, 6, 5, 5, 6, 5, 5, 6, 5, 5, 5, 9, 9, 5, 6, 5, 8, 5, 5

Offset

1,2

Comments

Exponents of 2 in -1+p^s if the exponent s[u]=(2^u)k-(2^(u-1) comes from other sequence generated with s[u-1] exponent by adding 1 to terms of the "previous" sequence. E.g. s=256k-128 needed an addition of 6 to the terms of A091282.

Links

Table of n, a(n) for n=1..50.

Mathematica

Table[{8*k-4, Table[Part[Flatten[FactorInteger [ -1+Prime[n]^(16*k-8)]], 2], {n, 2, 50}]}, {k, 1, 2}]

Crossrefs

Cf. A023506, A007814, A091282, A091283, A090739, A090740, A090129.

Sequence in context: A161981 A346962 A258072 * A276860 A046604 A377085

Adjacent sequences: A091281 A091282 A091283 * A091285 A091286 A091287

Keyword

nonn

Author

Labos Elemer, Jan 22 2004

Status

approved