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!)
 A329890 a(1) = 1; for n > 1, a(n) = sigma((2^n)-1) - sigma((2^(n-1))-1), where sigma is A000203, the sum of divisors. 4
 1, 3, 4, 16, 8, 72, 24, 304, 160, 944, 624, 6576, -544, 14336, 16384, 72544, 19616, 342528, 50688, 1475584, 466176, 3443712, 2657376, 29486880, -3340288, 54808448, 65971360, 306781024, 77647680, 1475408064, 132153344, 5157119680, 3054411072, 12548176896, 13343981568, 130039259136, -28235160128, 228451400256, 269821673472 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS FORMULA a(1) = 1; and for n > 1, a(n) = A075708(n) - A075708(n-1). PROG (PARI) A329890(n) = if(1==n, 1, sigma((2^n)-1)-sigma((2^(n-1))-1)); CROSSREFS From second term onwards, the first differences of A075708. Cf. A000203, A329637, A329891, A329892. Sequence in context: A041325 A042541 A325212 * A330299 A047164 A304988 Adjacent sequences:  A329887 A329888 A329889 * A329891 A329892 A329893 KEYWORD sign AUTHOR Antti Karttunen, Dec 08 2019 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 April 9 07:30 EDT 2020. Contains 333344 sequences. (Running on oeis4.)