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!)
A027388 Write digits for n, count endpoints (version 3). 3

%I #21 Nov 06 2017 04:33:41

%S 0,2,2,2,2,2,1,4,0,1,2,4,4,4,4,4,3,6,2,3,2,4,4,4,4,4,3,6,2,3,2,4,4,4,

%T 4,4,3,6,2,3,2,4,4,4,4,4,3,6,2,3,2,4,4,4,4,4,3,6,2,3,1,3,3,3,3,3,2,5,

%U 1,2,4,6,6,6,6,6,5,8,4,5,0

%N Write digits for n, count endpoints (version 3).

%C Number of endpoints: 0,8 - zero, 6,9 - one, 1,2,3,4,5 - two, 7 - four. - _Michael B. Porter_, Oct 28 2017

%F a(10*n + d) = a(n) + e where e is the number of endpoints of single digit d. - _David A. Corneth_, Oct 28 2017

%e The digit 1 has two endpoints, and the digit 8 has no endpoints, so a(18) = 2. - _Michael B. Porter_, Oct 28 2017

%o (PARI) a(n)=vecsum(apply(d->[0, 2, 2, 2, 2, 2, 1, 4, 0, 1][d+1], digits(n))); \\ based on program for A027386 by _Andrew Howroyd_, _Michael B. Porter_, Oct 28 2017

%Y Cf. A027386, A027387, A027389, A055642, A100910, A102683, A268643.

%K nonn,base

%O 0,2

%A _N. J. A. Sloane_

%E a(6) corrected by _Michael B. Porter_, Oct 28 2017 (per _Andrew Howroyd_)

%E a(27) to a(80) by _Michael B. Porter_, Oct 28 2017

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 March 28 08:22 EDT 2024. Contains 371236 sequences. (Running on oeis4.)