A151791 a(1)=1; for n > 1, a(n) = 7*6^(wt(n-1)-1).

1, 7, 7, 42, 7, 42, 42, 252, 7, 42, 42, 252, 42, 252, 252, 1512, 7, 42, 42, 252, 42, 252, 252, 1512, 42, 252, 252, 1512, 252, 1512, 1512, 9072, 7, 42, 42, 252, 42, 252, 252, 1512, 42, 252, 252, 1512, 252, 1512, 1512, 9072, 42, 252, 252, 1512, 252, 1512, 1512, 9072, 252

Offset: 1

Author

N. J. A. Sloane, Jun 25 2009

Keywords

• nonn
• tabf

Comments

wt(n) is the Hamming weight = binary weight of n (A000120).

Examples

			From _Omar E. Pol_, Feb 26 2015: (Start)
Written as an irregular triangle in which the row lengths are the terms of A011782 the sequence begins:
1;
7;
7,42;
7,42,42,252;
7,42,42,252,42,252,252,1512;
7,42,42,252,42,252,252,1512,42,252,252,1512,252,1512,1512,9072;
7,42,42,252,42,252,252,1512,42,252,252,1512,252,1512,1512,9072,42,252,252,1512,252,1512,1512,9072,252,...
It appears that the right border gives A003949.
It appears that the row sums give A000420.
(End)
		

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..8192

Crossrefs

Cf. A011782, A000120, A000420, A151792 (partial sums).

Programs

Mathematica

a[n_] := 7*6^(Total@ IntegerDigits[n - 1, 2] - 1); a[1] = 1; Array[a, 57] (* Michael De Vlieger, Nov 01 2022 *)