A236681 Positive integers a such that there exist integers b, c > 0 with 1/a + 1/b + 1/c = 1/2.

3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 18, 20, 24, 42

Offset

1,1

Comments

According to J. Baez, the reason why 42 is the Answer to the Ultimate Question of Life, the Universe, and Everything, cf. LINK.

A subsequence of A236681.

Links

Table of n, a(n) for n=1..14.

J. Baez, 42.

Example

The solutions [a,b,c] such that 1/a + 1/b + 1/c = 1/2 are {[3, 12, 12], [3, 7, 42], [3, 8, 24], [3, 9, 18], [3, 10, 15], [4, 5, 20], [4, 6, 12] [4, 8, 8], [5, 5, 10], [6, 6, 6]}.

Prog

(PARI) S=[]; for(a=2, 99, for(b=2, a, numerator(1/2-1/a-1/b)==1 && (S=setunion(S, Set([a, b, 1/(1/2-1/a-1/b)]))) && next(2))); S

Crossrefs

Sequence in context: A114036 A261793 A262288 * A160238 A039165 A138220

Adjacent sequences: A236678 A236679 A236680 * A236682 A236683 A236684

Keyword

nonn,fini,full

Author

M. F. Hasler, Jan 29 2014

Status

approved