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

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

Offset

0,2

Comments

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

Links

Table of n, a(n) for n=0..80.

Formula

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

Example

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

Prog

(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

Crossrefs

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

Sequence in context: A133563 A104518 A329030 * A114295 A004216 A076489

Adjacent sequences: A027385 A027386 A027387 * A027389 A027390 A027391

Keyword

nonn,base

Author

N. J. A. Sloane

Extensions

a(6) corrected by Michael B. Porter, Oct 28 2017 (per Andrew Howroyd)

a(27) to a(80) by Michael B. Porter, Oct 28 2017

Status

approved