A320229 Least semiprime from merging n consecutive semiprimes.

4, 46, 469, 25263334, 910141521, 469101415, 26333435383946, 3334353839464951, 91014152122252633, 65697477828586879193, 778285868791939495106111, 778285868791939495106111115118, 115118119121122123129133134141142143, 3538394649515557586265697477

Offset

1,1

Comments

Apparently a(n) exists for any n.

Links

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

Example

n = 14: 35-38-39-46-49-51-55-57-58-62-65-69-74-77 => 1540961*2296225958681340790757,
n = 15: 87-91-93-94-95-106-111-115-118-119-121-122-123-129-133 => 53*165885650851058700285247530587209870361,
n = 16: 6-9-10-14-15-21-22-25-26-33-34-35-38-39-46-49 => 43669*15823906023088521224290421.

Prog

(Perl) use ntheory ":all"; sub ls { my($n, $k, $s)=(shift, 0, 0); do { $k++; $s = fromdigits(join "", map { nth_semiprime($_) } $k .. $k+$n-1); } until is_semiprime($s); $s; } print "$_ ", ls($_), "\n" for 1..30; # Dana Jacobsen, Oct 19 2018

Crossrefs

Sequence in context: A132932 A231787 A173716 * A097952 A097643 A155652

Adjacent sequences: A320226 A320227 A320228 * A320230 A320231 A320232

Keyword

nonn,base

Author

Zak Seidov, Oct 08 2018

Status

approved