A087831 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

A087831

a(n) = a(abs(n-a(n-1))) + a(a(abs(n-a(n-4)))) if n>4, a(n) = 1 otherwise.

1, 1, 1, 1, 1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5, 7, 6, 7, 7, 7, 7, 7, 10, 7, 10, 10, 8, 10, 10, 10, 11, 10, 14, 10, 13, 14, 14, 11, 14, 14, 11, 15, 14, 14, 15, 15, 15, 18, 15, 17, 15, 18, 17, 19, 19, 18, 19, 19, 19, 16, 20, 20, 19, 20, 20, 20, 20, 23, 20, 22, 20, 23, 22, 23, 25

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

OFFSET

0,6

COMMENTS

Second type of triple recursion for the skip two Hofstadter Q.

LINKS

Table of n, a(n) for n=0..78.

MATHEMATICA

Hofstadter14[n_Integer?Positive] := Hofstadter14[n] = Hofstadter14[Abs[n - Hofstadter14[n-1]]] + Hofstadter14[ Hofstadter14[Abs[n - Hofstadter14[n-4]]]] Hofstadter14[0] = Hofstadter14[1] = Hofstadter14[2]= Hofstadter14[3]= Hofstadter14[4]= 1 digits=200 ta=Table[Hofstadter14[n], {n, 1, digits}]

CROSSREFS

Cf. A005185.

Sequence in context: A341510 A196238 A087843 * A351960 A372759 A194327

Adjacent sequences: A087828 A087829 A087830 * A087832 A087833 A087834

KEYWORD

nonn

AUTHOR

Roger L. Bagula, Oct 06 2003

EXTENSIONS

Inserted a(0)=1 by Paolo P. Lava, Mar 12 2012

STATUS

approved