A074487 a(1)=1, then "jump over next square": a(n) = 2*(a(n-1)+1)^2-a(n-1).

1, 7, 121, 29647, 1757978161, 6180974434379818327, 76408889916913830205838054898189612841, 11676636916670111980512852400247542904848802859324947344926081051625513021087

Offset

1,2

Comments

The rule "jump over next something" can be varied, see A075694, A075695.

Links

Table of n, a(n) for n=1..8.

Formula

a(1)=1, a(n) = 2*(a(n-1)+1)^2 - a(n-1).

Example

a(1)=1; next square is (a(1)+1)^2=4; "jump over" it: 4+(4-1)=7; a(2)=7; next square is (a(2)+1)^2=64; "jump over" it: 64+(64-7)=121.

Maple

a(1) := 1; a(n) := 2*(a(n-1)+1)^2-a(n-1);

Crossrefs

Cf. A075694, A075695.

Sequence in context: A211103 A012103 A012086 * A192566 A322090 A360337

Adjacent sequences: A074484 A074485 A074486 * A074488 A074489 A074490

Keyword

easy,nonn

Author

Zak Seidov, Sep 26 2002

Status

approved