A133393 Start with a(1)=1; for n >= 1, a(n+1)=a(n)+a(k) with k=[n - n-th digit of sqrt(2)]. If k<0 or k=0, then a(k)=0.

1, 1, 1, 2, 2, 3, 5, 7, 8, 9, 16, 23, 25, 34, 68, 71, 87, 174, 208, 224, 247, 494, 741, 828, 899, 986, 1194, 2093, 2921, 4115, 8230, 8724, 9710, 10538, 11524, 23048, 25969, 28890, 38600, 48310, 56540, 68064, 79588, 147652, 170700, 199590, 256130, 403782

Offset

1,4

Comments

Terms computed by Gilles Sadowski.

Links

Gilles Sadowski, Table of n, a(n) for n = 1..101

Example

For n=7 we have a(8)=a(7)+a(k) with k=(7-3) because "3" is the 7th digit of sqrt(2): 1,4,1,4,2,1,(3),5,6,2,3,... So a(8)=a(7)+a(4)=5+2=7.

Crossrefs

Sequence in context: A245935 A178880 A079953 * A126881 A290273 A125505

Adjacent sequences: A133390 A133391 A133392 * A133394 A133395 A133396

Keyword

base,easy,nonn

Author

Eric Angelini, Nov 23 2007

Status

approved