A337383 a(n) = 1 if sigma(A003961(n)) >= 2*sigma(n), 0 otherwise, where A003961 is the prime shift towards larger primes.

0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1

Offset

1

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index entries for characteristic functions

Index entries for sequences computed from indices in prime factorization

Index entries for sequences related to sigma(n)

Formula

a(n) = 1 if A003973(n) >= 2*A000203(n), 0 otherwise.

Prog

(PARI)
A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
A337383(n) = (sigma(A003961(n))>=2*sigma(n));

Crossrefs

Characteristic function of A337381.

Cf. A000203, A003961, A003973, A337382 (positions of zeros).

Cf. also A252742, A337380.

Sequence in context: A156659 A011671 A086483 * A011667 A144195 A226464

Adjacent sequences: A337380 A337381 A337382 * A337384 A337385 A337386

Keyword

nonn

Author

Antti Karttunen, Aug 27 2020

Status

approved