A061501 a(1) = 1, a(n+1) = (a(n) + n) mod 10.

1, 2, 4, 7, 1, 6, 2, 9, 7, 6, 6, 7, 9, 2, 6, 1, 7, 4, 2, 1, 1, 2, 4, 7, 1, 6, 2, 9, 7, 6, 6, 7, 9, 2, 6, 1, 7, 4, 2, 1, 1, 2, 4, 7, 1, 6, 2, 9, 7, 6, 6, 7, 9, 2, 6, 1, 7, 4, 2, 1, 1, 2, 4, 7, 1, 6, 2, 9, 7, 6, 6, 7, 9, 2, 6, 1, 7, 4, 2, 1, 1, 2, 4, 7, 1, 6, 2, 9, 7, 6, 6, 7, 9, 2, 6, 1, 7, 4, 2, 1, 1, 2, 4, 7, 1

Offset

1,2

Comments

First row of array shown below.

a(n) = most significant digit of A062273(n).

Period 20: repeat [1, 2, 4, 7, 1, 6, 2, 9, 7, 6, 6, 7, 9, 2, 6, 1, 7, 4, 2, 1]. - Peter M. Chema, Feb 12 2017

Links

Table of n, a(n) for n=1..105.

Formula

a(n) = A008954(n-1) + 1.

a(n) = A000124(n) mod 10. - Peter M. Chema, Feb 11 2017

From Chai Wah Wu, Jan 09 2020: (Start)

a(n) = a(n-5) - a(n-10) + a(n-15) for n > 15.

G.f.: x*(-x^14 - 2*x^13 - 4*x^12 - 7*x^11 - x^10 - 5*x^9 - 5*x^7 - 5*x^5 - x^4 - 7*x^3 - 4*x^2 - 2*x - 1)/(x^15 - x^10 + x^5 - 1). (End)

Example

1 2 4 7 1 6 2 9 7 6 6 ...
3 5 8 2 7 3 0 8 7 7 ...
6 9 3 8 4 1 9 8 8 ...
0 4 9 5 2 0 9 9 ...
5 0 6 3 1 0 0 ...
1 7 4 2 1 1 ...

Mathematica

a = {1}; Do[AppendTo[a, Mod[a[[n - 1]] + n - 1, 10]], {n, 2, 120}]; a (* Michael De Vlieger, Feb 13 2017 *)

Prog

(PARI) a(n)=if(n==1, return(1)); (a(n-1)+n-1)%10
for(n=1, 50, print1(a(n), ", ")) \\ Derek Orr, Feb 26 2017

Crossrefs

Cf. A061352, A061353.

Cf. A062273, A077577, A077578.

Cf. A000124.

Sequence in context: A097879 A180658 A019748 * A272001 A089349 A118424

Adjacent sequences: A061498 A061499 A061500 * A061502 A061503 A061504

Keyword

base,nonn,less

Author

Amarnath Murthy, May 06 2001

Extensions

Better description and more terms from Larry Reeves (larryr(AT)acm.org), May 08 2001

Status

approved