A062306 Number of ways writing 2^n as a sum of two nonprime numbers.

1, 0, 1, 4, 7, 19, 36, 82, 170, 362, 740, 1537, 3144, 6443, 13116, 26661, 54034, 109386, 221121, 446502, 900436, 1814910, 3655069, 7356483, 14796994, 29750473, 59789057, 120112121, 241218391, 484287995, 972034297, 1950544851, 3913243144, 7849331541, 15741697002

Offset

1,4

Links

Amiram Eldar, Table of n, a(n) for n = 1..40

Formula

a(n) = A062610(2^n) = number of nonprime+nonprime partitions of 2^n.

a(n) = 2^(n-1) - A006307(n) - A062305(n). - Amiram Eldar, Jul 17 2024

Example

For n = 5: 2^5 = 32 = 4+28 = 6+26 = 8+24 = 10+22 = 12+20 = 14+18 = 16+16, so a(5) = 7.

Crossrefs

Cf. A061358, A062602, A062305, A006307, A062610.

Sequence in context: A298350 A291596 A323655 * A323105 A006130 A140167

Adjacent sequences: A062303 A062304 A062305 * A062307 A062308 A062309

Keyword

nonn

Author

Labos Elemer, Jul 05 2001

Extensions

More terms from Dean Hickerson, Jul 23, 2001

a(28)-a(32) from Sean A. Irvine, Mar 25 2023

a(33)-a(35) from Amiram Eldar, Jul 17 2024

Status

approved