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!)
 A083238 First order recursion: a(0)=1; a(n) = sigma(1,n) - a(n-1). 2
 1, 0, 3, 1, 6, 0, 12, -4, 19, -6, 24, -12, 40, -26, 50, -26, 57, -39, 78, -58, 100, -68, 104, -80, 140, -109, 151, -111, 167, -137, 209, -177, 240, -192, 246, -198, 289, -251, 311, -255, 345, -303, 399, -355, 439, -361, 433, -385, 509, -452, 545, -473, 571, -517, 637, -565, 685, -605, 695, -635, 803, -741, 837, -733, 860 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Provide interesting decomposition: sigma(n)=u+w, where u and w consecutive terms of this sequence; this depends also on initial value. LINKS FORMULA It follows that a(n)+a(n-1) = A000203(n). MATHEMATICA f[x_] := DivisorSigma[1, x]-f[x-1] f[0]=1; Table[f[w], {w, 1, 100}] PROG (PARI) lista(nn) = {my(last = 1, v=vector(nn)); for (n=1, nn, v[n] = sigma(n) - last; last = v[n]; ); concat(1, v); } \\ Michel Marcus, Mar 28 2020 CROSSREFS Cf. A000203, A083236, A083237. Sequence in context: A298241 A113817 A197151 * A337604 A117782 A317855 Adjacent sequences:  A083235 A083236 A083237 * A083239 A083240 A083241 KEYWORD sign AUTHOR Labos Elemer, Apr 23 2003 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 12 10:52 EDT 2021. Contains 342920 sequences. (Running on oeis4.)