A054425 - OEIS

A054425

A054424 expanded to normal triangular array, with zeros at those (x,y) where x and y are not relatively prime.

1, 2, 3, 4, 0, 7, 8, 5, 6, 15, 16, 0, 0, 0, 31, 32, 9, 11, 12, 14, 63, 64, 0, 10, 0, 13, 0, 127, 128, 17, 0, 23, 24, 0, 30, 255, 256, 0, 19, 0, 0, 0, 28, 0, 511, 512, 33, 18, 20, 47, 48, 27, 29, 62, 1023, 1024, 0, 0, 0, 22, 0, 25, 0, 0, 0, 2047, 2048, 65, 35, 39, 21, 95, 96, 26, 56

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

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..75.

MAPLE

position_in_whole_SB_tree_or_zero := (n, m) -> `if`((1 = gcd(n, m)), (frac2position_in_whole_SB_tree(n/m)), (0));

A054424_as_array := n -> position_in_whole_SB_tree_or_zero( ((n-((trinv(n)*(trinv(n)-1))/2))+1), ((((trinv(n)-1)*(((1/2)*trinv(n))+1))-n)+1) );

trinv := n -> floor((1+sqrt(1+8*n))/2); # Gives integral inverses to the triangular numbers

CROSSREFS

Cf. A054424, A054431.

Sequence in context: A004180 A011418 A214158 * A217101 A265516 A256295

Adjacent sequences: A054422 A054423 A054424 * A054426 A054427 A054428

KEYWORD

nonn,tabl,nice

AUTHOR

Antti Karttunen

STATUS

approved