login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A263085 Partial sums of A099774 (A099774(n) = number of divisors of n-th odd number). 5
1, 3, 5, 7, 10, 12, 14, 18, 20, 22, 26, 28, 31, 35, 37, 39, 43, 47, 49, 53, 55, 57, 63, 65, 68, 72, 74, 78, 82, 84, 86, 92, 96, 98, 102, 104, 106, 112, 116, 118, 123, 125, 129, 133, 135, 139, 143, 147, 149, 155, 157, 159, 167, 169, 171, 175, 177, 181, 187, 191, 194, 198 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10082

FORMULA

a(1) = 1; for n > 1, a(n) = A000005((2*n)-1) + a(n-1). [Where A000005(k) gives the number of divisors of k.]

Other identities. For all n >= 1:

a(n) = A263086(n) - A263084(n).

MATHEMATICA

FoldList[DivisorSigma[0, 2*#2-1]+#1&, 1, Range[2, 62]] (* Ivan N. Ianakiev, Oct 24 2015 *)

PROG

(Scheme, with memoization-macro definec)

(definec (A263085 n) (if (= 1 n) (A099774 n) (+ (A099774 n) (A263085 (- n 1)))))

(PARI) lista(nn) = {s = 0; forstep (n=1, nn, 2, s += numdiv(n); print1(s, ", "); ); } \\ Michel Marcus, Oct 12 2015

CROSSREFS

Cf. A000005, A006218, A099774, A263086.

Sequence in context: A033035 A047390 A184653 * A206334 A184741 A020959

Adjacent sequences:  A263082 A263083 A263084 * A263086 A263087 A263088

KEYWORD

nonn

AUTHOR

Antti Karttunen, Oct 12 2015

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 19 18:28 EDT 2018. Contains 316377 sequences. (Running on oeis4.)