A382162 Number of pairs (i,j), 1 <= i < j <= n such that A019444(i) < A019444(j).

0, 1, 2, 5, 9, 12, 18, 22, 30, 39, 45, 56, 68, 76, 90, 99, 115, 132, 143, 162, 174, 195, 217, 231, 255, 280, 296, 323, 340, 369, 399, 418, 450, 483, 504, 539, 561, 598, 636, 660, 700, 725, 767, 810, 837, 882, 928, 957, 1005, 1035, 1085, 1136, 1168, 1221, 1254, 1309, 1365, 1400, 1458, 1517, 1554, 1615, 1653, 1716, 1780, 1820

Offset

1,3

Comments

The count of pairs with A019444(i) > A019444(j) gives triangular numbers and is less interesting.

Links

Table of n, a(n) for n=1..66.

Crossrefs

Cf. A019444.

Sequence in context: A034806 A226822 A034307 * A239876 A070828 A112988

Adjacent sequences: A382159 A382160 A382161 * A382163 A382164 A382165

Keyword

nonn

Author

N. J. A. Sloane, Mar 31 2025

Status

approved