A073718 Powers of 2 with composite exponents.

16, 64, 256, 512, 1024, 4096, 16384, 32768, 65536, 262144, 1048576, 2097152, 4194304, 16777216, 33554432, 67108864, 134217728, 268435456, 1073741824, 4294967296, 8589934592, 17179869184, 34359738368, 68719476736

Offset

1,1

Links

Table of n, a(n) for n=1..24.

Index to divisibility sequences

Formula

a(n) = 2^A002808(n) = A000079(A002808(n)).

Sum_{n>=1} 1/a(n) = A275306. - Amiram Eldar, Aug 11 2020

Mathematica

Table[2^FixedPoint[n+PrimePi[ # ]+1&, n], {n, 1, 30}]

Prog

(PARI) for(n=4, 100, if(!isprime(n), print1(2^n", "))) \\ Charles R Greathouse IV, Apr 09 2012

Crossrefs

Cf. A000079, A002808, A275306.

Sequence in context: A212512 A317235 A255661 * A230970 A352738 A061449

Adjacent sequences: A073715 A073716 A073717 * A073719 A073720 A073721

Keyword

easy,nonn

Author

Labos Elemer, Aug 05 2002

Status

approved