A379222 Number of trailing 1-bits in the binary representation of the sum of the divisors of the n-th odd square: a(n) = sigma((2*n-1)^2).

1, 1, 5, 1, 1, 1, 3, 2, 2, 1, 1, 1, 1, 1, 3, 1, 1, 3, 7, 2, 2, 1, 3, 1, 1, 3, 4, 2, 1, 1, 3, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 2, 6, 1, 2, 2, 1, 6, 1, 2, 1, 3, 2, 2, 3, 7, 2, 1, 7, 2, 1, 1, 1, 1, 2, 2, 1, 1, 2, 1, 1, 4, 1, 2, 6, 3, 2, 1, 1, 5, 1, 1, 1, 3, 1, 1, 1, 4, 2, 1, 7, 1, 1, 2, 1, 5, 1, 1, 4, 1, 1, 1

Offset

1,3

Links

Antti Karttunen, Table of n, a(n) for n = 1..20000

Index entries for sequences related to binary expansion of n.

Index entries for sequences related to sigma(n).

Formula

a(n) = A378999(2*n-1) = A378998(A016754(n-1)) = A007814(1+A000203(A016754(n-1))).

Mathematica

IntegerExponent[DivisorSigma[1, (2*Range[100] - 1)^2] + 1, 2] (* Paolo Xausa, Jan 23 2025 *)

Prog

(PARI) A379222(n) = valuation(1+sigma((2*n-1)^2), 2);

Crossrefs

Odd bisection of A378999.

Cf. A000203, A007814, A016754, A378998.

Sequence in context: A026518 A362394 A345949 * A348505 A051008 A304042

Adjacent sequences: A379219 A379220 A379221 * A379223 A379224 A379225

Keyword

nonn

Author

Antti Karttunen, Dec 22 2024

Status

approved