A309721 Number of right angles between the segments that are turned "on" when representing n on a 7-segment (calculator) display.

4, 0, 4, 4, 3, 4, 6, 1, 8, 6, 4, 0, 4, 4, 3, 4, 6, 1, 8, 6, 8, 4, 8, 8, 7, 8, 10, 5, 12, 10, 8, 4, 8, 8, 7, 8, 10, 5, 12, 10, 7, 3, 7, 7, 6, 7, 9, 4, 11, 9, 8, 4, 8, 8, 7, 8, 10, 5, 12, 10, 10, 6, 10, 10, 9, 10, 12, 7, 14, 12, 5, 1, 5, 5, 4, 5, 7, 2, 9, 7, 12, 8, 12, 12, 11, 12, 14, 9, 16, 14, 10, 6, 10, 10, 9, 10, 12, 7

Offset

0,1

Comments

The display is the one described in A006942 (see also the example section below).

Links

Table of n, a(n) for n=0..97.

Formula

a(n) = a(floor(n/10)) + a(n mod 10), for n > 9 (a formula by Reinhard Zumkeller, same for A006942 and A010371).

Example

To illustrate a(0),...,a(9):
   _     _  _       _   _   _   _   _
  | | |  _| _| |_| |_  |_    | |_| |_|
  |_| | |_  _|   |  _| |_|   | |_|  _|
.

Mathematica

Evaluate[Table[a[n], {n, 0, 9}]]={4, 0, 4, 4, 3, 4, 6, 1, 8, 6};
a[n_/; n>9]:=a[Floor[n/10]]+a[Mod[n, 10]]; a/@Range[0, 100] (* or *)
Table[Total[IntegerDigits[n]/.{0->4, 1->0, 2->4, 3->4, 4-> 3, 5->4, 7->1, 9->6}], {n, 0, 100}]

Crossrefs

Cf. A006942, A010371, A063720, A277116.

Sequence in context: A152856 A031362 A198414 * A110854 A278086 A021716

Adjacent sequences: A309718 A309719 A309720 * A309722 A309723 A309724

Keyword

nonn,base,easy

Author

Ivan N. Ianakiev, Aug 14 2019

Status

approved