The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A339603 a(n) is the sum of (2^n mod k) for odd numbers k < 2^(n-1). 0
 0, 0, 2, 4, 31, 103, 439, 1665, 6942, 27598, 110371, 438843, 1762848, 7052170, 28211223, 112799719, 451277874, 1804973952, 7220128542, 28880086112, 115521335176, 462085087138, 1848340368720, 7393350063050, 29573434659318, 118293733260264, 473174926753087 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Primes in this sequence include a(3) = 2, a(5) = 31, a(6) = 103, a(7) = 439, and a(16) = 112799719. LINKS EXAMPLE a(4) = (2^4 mod 1) + (2^4 mod 3) + (2^4 mod 5) + (2^4 mod 7) = 0+1+1+2 = 4. MAPLE f:= proc(m) local t; add(m mod t, t=1..m/2, 2) end proc: seq(f(2^i), i=1..27); PROG (PARI) a(n) = sum(k=0, 2^(n-2)-1, lift(Mod(2, 2*k+1)^n)); \\ Michel Marcus, Dec 22 2020 CROSSREFS Sequence in context: A296249 A181620 A220283 * A188113 A259115 A051569 Adjacent sequences:  A339600 A339601 A339602 * A339604 A339605 A339606 KEYWORD nonn AUTHOR J. M. Bergot and Robert Israel, Dec 22 2020 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
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified June 12 06:52 EDT 2021. Contains 344943 sequences. (Running on oeis4.)