A370831 Alternating sum of composites.

4, 2, 6, 3, 7, 5, 9, 6, 10, 8, 12, 9, 13, 11, 14, 12, 15, 13, 17, 15, 18, 16, 19, 17, 21, 18, 22, 20, 24, 21, 25, 23, 26, 24, 27, 25, 29, 26, 30, 27, 31, 29, 33, 30, 34, 31, 35, 33, 36, 34, 38, 36, 39, 37, 40, 38, 42, 39, 43, 41, 44, 42, 45, 43, 47, 44, 48, 45, 49, 46

Offset

1,1

Comments

Unlike equivalent sequence for primes, A008347, there are repeated terms.

Links

Table of n, a(n) for n=1..70.

Formula

a(n) = A002808(n) - a(n-1), for n>1.

Example

a(4) = 9 - 8 + 6 - 4 = 3.

Mathematica

Join[{4}, a[1]=4; a[n_]:=ResourceFunction["Composite"][n] - a[n-1]; Table[a[n], {n, 2, 70}]] (* or with signs *) R=70; a[1]=4; a[n_]:=a[n-1]-ResourceFunction["Composite"][n] *(-1)^n; Table[a[n], {n, 70}]

Crossrefs

Cf. A002808, A008347.

Sequence in context: A246879 A302794 A247361 * A297307 A163238 A097362

Adjacent sequences: A370828 A370829 A370830 * A370832 A370833 A370834

Keyword

nonn

Author

James C. McMahon, Mar 02 2024

Status

approved