1.7 KiB
id, title, challengeType, forumTopicId, dashedName
id | title | challengeType | forumTopicId | dashedName |
---|---|---|---|---|
5900f5411000cf542c510052 | Problem 467: Superinteger | 5 | 302142 | problem-467-superinteger |
--description--
An integer s
is called a superinteger of another integer n
if the digits of n
form a subsequence of the digits of s
.
For example, 2718281828 is a superinteger of 18828, while 314159 is not a superinteger of 151.
Let p(n)
be the $n$th prime number, and let c(n)
be the $n$th composite number. For example, p(1) = 2
, p(10) = 29
, c(1) = 4
and c(10) = 18
.
\begin{align} & \\{p(i) : i ≥ 1\\} = \\{2, 3, 5, 7, 11, 13, 17, 19, 23, 29, \ldots \\} \\\\ & \\{c(i) : i ≥ 1\\} = \\{4, 6, 8, 9, 10, 12, 14, 15, 16, 18, \ldots \\} \end{align}
Let P^D
the sequence of the digital roots of \\{p(i)\\}
(C^D
is defined similarly for \\{c(i)\\}
):
\begin{align} & P^D = \\{2, 3, 5, 7, 2, 4, 8, 1, 5, 2, \ldots \\} \\\\ & C^D = \\{4, 6, 8, 9, 1, 3, 5, 6, 7, 9, \ldots \\} \end{align}
Let P_n
be the integer formed by concatenating the first n
elements of P^D
(C_n
is defined similarly for C^D
).
\begin{align} & P_{10} = 2\\,357\\,248\\,152 \\\\ & C_{10} = 4\\,689\\,135\\,679 \end{align}
Let f(n)
be the smallest positive integer that is a common superinteger of P_n
and C_n
. For example, f(10) = 2\\,357\\,246\\,891\\,352\\,679
, and f(100)\bmod 1\\,000\\,000\\,007 = 771\\,661\\,825
.
Find f(10\\,000)\bmod 1\\,000\\,000\\,007
.
--hints--
superinteger()
should return 775181359
.
assert.strictEqual(superinteger(), 775181359);
--seed--
--seed-contents--
function superinteger() {
return true;
}
superinteger();
--solutions--
// solution required