A027386 - OEIS

A027386

Write digits for n, count endpoints (version 1).

0, 2, 2, 2, 2, 2, 1, 2, 0, 1, 2, 4, 4, 4, 4, 4, 3, 4, 2, 3, 2, 4, 4, 4, 4, 4, 3, 4, 2, 3, 2, 4, 4, 4, 4, 4, 3, 4, 2, 3, 2, 4, 4, 4, 4, 4, 3, 4, 2, 3, 2, 4, 4, 4, 4, 4, 3, 4, 2, 3, 1, 3, 3, 3, 3, 3, 2, 3, 1, 2, 2, 4, 4, 4, 4, 4, 3, 4, 2, 3, 0

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,2

COMMENTS

Number of endpoints: 0,8 - zero, 6,9 - one, 1,2,3,4,5,7 - two. - 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

MATHEMATICA

Table[Total[IntegerDigits[n]/.{0->0, 1->2, 2->2, 3->2, 4->2, 5->2, 6->1, 7->2, 8->0, 9->1}], {n, 0, 80}] (* Harvey P. Dale, Apr 28 2018 *)

PROG

(PARI) a(n)=vecsum(apply(d->[0, 2, 2, 2, 2, 2, 1, 2, 0, 1][d+1], digits(n))); \\ Andrew Howroyd, Oct 26 2017

CROSSREFS

Cf. A027387, A027388, A027389, A055642, A100910, A102683, A268643.

Sequence in context: A159700 A083534 A174664 * A102300 A359511 A202146

Adjacent sequences: A027383 A027384 A027385 * A027387 A027388 A027389

KEYWORD

nonn,base

AUTHOR

N. J. A. Sloane.

EXTENSIONS

a(6) corrected and a(27)-a(80) from Andrew Howroyd, Oct 26 2017

STATUS

approved