A053231 First differences between n for which sigma(n) < sigma(n+1), which are not 2.

1, 1, 4, 1, 1, 1, 1, 4, 4, 1, 1, 1, 1, 4, 1, 1, 4, 1, 1, 4, 4, 1, 3, 4, 4, 1, 1, 1, 3, 1, 1, 4, 1, 1, 1, 1, 4, 1, 3, 1, 1, 4, 1, 1, 4, 1, 1, 4, 1, 1, 1, 1, 1, 1, 1, 3, 4, 1, 1, 1, 1, 1, 3, 4, 1, 1, 1, 1, 4, 4, 1, 1, 4, 4, 1, 1, 1, 3, 4, 1, 1, 1, 1, 4, 1, 1, 1, 1, 4, 1, 3, 1, 3, 4, 4, 1, 1, 1, 1, 4, 1, 1, 4, 1, 1

Offset

1,3

Links

Table of n, a(n) for n=1..105.

Formula

The expansion of A053230 excluding 2's. a(n) = A053230(A053232(n)).

Maple

with(numtheory): f := [seq( `if`((sigma(i+1) > sigma(i)), i, print( )), i=1..5000)];
seq( `if`(f[i+1] - f[i] <> 2, f[i+1] - f[i], print( )), i=1..2000);

Crossrefs

Cf. A000203, A053224, A053230, A053232, A053233, A053234, A053235, A053236, A053237.

Sequence in context: A196879 A193349 A380587 * A379545 A066701 A046563

Adjacent sequences: A053228 A053229 A053230 * A053232 A053233 A053234

Keyword

nonn

Author

Asher Auel, Jan 10 2000

Status

approved