A161341 - OEIS

A161341

First differences of A161340.

1, 26, 56, 260, 56, 392, 392, 2192, 56, 392, 392, 2744, 392, 2744, 2744, 16952, 56, 392, 392, 2744, 392, 2744, 2744, 19208, 392, 2744, 2744, 19208, 2744, 19208, 19208, 125336, 56, 392, 392, 2744, 392, 2744, 2744, 19208, 392, 2744, 2744, 19208, 2744, 19208, 19208

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..47.

FORMULA

a(n) = A160429(n) for n>1 and n not a power of 2.

a(n) = A160429(n) - 3n*(3n - 1) for n>1 and n a power of 2.

EXAMPLE

From Omar E. Pol, Mar 15 2020: (Start)

Written as an irregular triangle in which row lengths give A011782 the sequence begins:

26;

56, 260;

56, 392, 392, 2192;

56, 392, 392, 2744, 392, 2744, 2744, 16952;

56, 392, 392, 2744, 392, 2744, 2744, 19208, 392, 2744, 2744, 19208, 2744, ...

(End)

PROG

(PARI) f(n) = 8*7^hammingweight(n-1); \\ A160429

ispow2(n) = my(k); (n==2) || (ispower(n, , &k) && (k==2));

a(n) = if (n==1, 1, if (ispow2(n), f(n) - 3*n*(3*n - 1), f(n))); \\ Michel Marcus, Mar 15 2020

CROSSREFS

Cf. A011782, A160414, A161340, A161415.

Sequence in context: A184839 A038848 A245004 * A038861 A277976 A291105

Adjacent sequences: A161338 A161339 A161340 * A161342 A161343 A161344

KEYWORD

nonn,tabf

AUTHOR

Omar E. Pol, Jun 14 2009

EXTENSIONS

Formula and more terms from Nathaniel Johnston, Nov 15 2010

More terms from Jinyuan Wang, Mar 14 2020

STATUS

approved