A179860 -id:A179860 - cp's OEIS frontend

A179859 Numbers k that divide the sum of the first k noncomposites.

1, 3, 7, 225, 487, 735, 50047, 142835, 170209, 249655, 316585343, 374788043, 2460457827, 2803329305, 6860334657, 65397031525, 78658228039

Offset: 1

Ray Chandler, Jul 29 2010

A variant of A045345 (primes), A053781 (composites) and A129749 (nonprimes).

			The sum of the first 7 noncomposites is 42 = 6*7, so 7 is in the sequence.

Cf. A008578 (noncomposites), A014284 (sum of first n noncomposites).

Cf. A045345, A053781, A129749, A179860, A179861.

lista(kmax) = {my(m = 1, s = 1); print1(1, ", "); forprime(k = 1, kmax, m++; s += k; if(!(s % m), print1(m, ", ")));} \\ Amiram Eldar, May 24 2024

Numbers k such that k | A014284(k).
a(n) = A179861(n) / A179860(n).
a(n+1) = A158682(n) + 1.

a(16)-a(17) from Amiram Eldar, May 24 2024

A179861 a(n) is the sum of the first A179859(n) noncomposites.

Original entry on oeis.org

1, 6, 42, 143100, 775304, 1891890, 14646554832, 130985694070, 188757015148, 419047914740, 1055777525624570390, 1492138298614167680, 70288308055831268412, 91779857115464381780, 571686203669195590338, 56978071532766214007450, 83023388015844408083484

Offset: 1

Ray Chandler, Jul 29 2010

nonn

A variant of A050247 (primes), A073262 (composites) and A164280 (nonprimes).

			A179859(3) = 7; sum of first 7 noncomposites is 42, so a(3) = 42.

Cf. A008578 (noncomposites), A014284 (sum of first n noncomposites).

Cf. A050247, A073262, A164280, A179859, A179860.

a(n) = A014284(A179859(n)) = A179859(n) * A179860(n).

a(16)-a(17) from Amiram Eldar, May 24 2024

cp's OEIS Frontend

A179859 Numbers k that divide the sum of the first k noncomposites.

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