login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A277197 First differences of A260443. 3
1, 1, 3, -1, 13, -3, 15, -23, 83, -15, 195, -235, 415, -345, 105, -199, 619, -105, 6225, -6505, 20005, -17625, 6825, -9373, 15673, -12075, 43575, -46865, 21665, -20895, 1155, -2297, 6917, -1155, 324975, -328055, 3541055, -3415125, 1525125, -1652903, 4960403, -4318125, 52513125, -53137385, 24787385, -24604125, 525525, -727507, 1212607, -929775, 57598275 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
Two observations (not yet proved): from n=3 onward each term is alternatively negative and positive, and from n=4 onward the terms a(2n-1) and a(2n) seem to have at least the rightmost digit same in their decimal representation.
LINKS
FORMULA
a(n) = A260443(n+1) - A260443(n).
MATHEMATICA
a[n_] := a[n] = Which[n < 2, n + 1, EvenQ@ n, Times @@ Map[#1^#2 & @@ # &, FactorInteger[#] /. {p_, e_} /; e > 0 :> {Prime[PrimePi@ p + 1], e}] - Boole[# == 1] &@ a[n/2], True, a[#] a[# + 1] &[(n - 1)/2]]; Differences@ Table[a@ n, {n, 0, 51}] (* Michael De Vlieger, Apr 05 2017 *)
PROG
(Scheme) (define (A277197 n) (- (A260443 (+ 1 n)) (A260443 n)))
CROSSREFS
Cf. A260443.
Cf. also A277198.
Sequence in context: A170910 A134768 A295827 * A297898 A322384 A360088
KEYWORD
sign,look
AUTHOR
Antti Karttunen, Oct 10 2016
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 21 10:46 EDT 2024. Contains 371852 sequences. (Running on oeis4.)