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!)
 A340536 Digital root of 2*n^2. 0
 2, 8, 9, 5, 5, 9, 8, 2, 9, 2, 8, 9, 5, 5, 9, 8, 2, 9, 2, 8, 9, 5, 5, 9, 8, 2, 9, 2, 8, 9, 5, 5, 9, 8, 2, 9, 2, 8, 9, 5, 5, 9, 8, 2, 9, 2, 8, 9, 5, 5, 9, 8, 2, 9, 2, 8, 9, 5, 5, 9, 8, 2, 9, 2, 8, 9, 5, 5, 9, 8, 2, 9, 2, 8, 9, 5, 5, 9, 8, 2, 9, 2, 8, 9, 5, 5, 9, 8, 2, 9 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Period 9: repeat [2, 8, 9, 5, 5, 9, 8, 2, 9]. This sequence is also right if digital root of factor in "2*n^2" is 2 (for example, "11*n^2", "20*n^2", "29*n^2", etc.) LINKS Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,0,1). FORMULA a(n) = A010888(A001105(n)). EXAMPLE For n=5, 2*5^2 = 50 and digital root is 5, so a(5) = 5. PROG (PARI) dr(n) = if(n, (n-1)%9+1); \\ A010888 a(n) = dr(2*n^2); \\ Michel Marcus, Jan 21 2021 CROSSREFS Cf. A001105, A010888, A056992. Sequence in context: A179377 A199274 A140241 * A340778 A108744 A195724 Adjacent sequences:  A340533 A340534 A340535 * A340537 A340538 A340539 KEYWORD nonn,base,easy AUTHOR Radaev Nikita, Jan 10 2021 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 August 1 19:59 EDT 2021. Contains 346402 sequences. (Running on oeis4.)