A101680 A modular binomial transform of 10^n.

1, 11, 111, 1011, 10111, 111011, 1100111, 10001011, 100010111, 1100111011, 11101100111, 101110001011, 1011000010111, 11100000111011, 110000001100111, 1000000010001011, 10000000100010111, 110000001100111011, 1110000011101100111, 10110000101110001011, 101110001011000010111

Offset

0,2

Links

Table of n, a(n) for n=0..20.

Formula

a(n) = Sum{k=0..n} mod(binomial(2n-k, k), 2)*10^k<;

Prog

(Python)
def A101680(n): return sum(int(not ~((n<<1)-k)&k)*10**k for k in range(n+1)) # Chai Wah Wu, Jul 30 2025
(PARI) a(n) = sum(k=0, n, lift(Mod(binomial(2*n-k, k), 2))*10^k); \\ Michel Marcus, Jul 31 2025

Crossrefs

A099902 in binary. Bisection of A101623.

Sequence in context: A284400 A284541 A267051 * A267356 A215559 A346231

Adjacent sequences: A101677 A101678 A101679 * A101681 A101682 A101683

Keyword

easy,nonn

Author

Paul Barry, Dec 11 2004

Extensions

More terms from Michel Marcus, Jul 31 2025

Status

approved