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PROJECT EULER · #0467

Superinteger

Statement only · UnsolvedOriginal problem ↗

An integer s is called a superinteger of another integer n if the digits of n form a subsequenceA subsequence is a sequence that can be derived from another sequence by deleting some elements without changing the order of the remaining elements. 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 nth prime number, and let c(n) be the nth composite number. For example, p(1)=2, p(10)=29, c(1) = 4 and c(10)=18.
{p(i):i1}={2,3,5,7,11,13,17,19,23,29,}
{c(i):i1}={4,6,8,9,10,12,14,15,16,18,}

Let PD be the sequence of the digital roots of {p(i)} (CD is defined similarly for {c(i)}):
PD={2,3,5,7,2,4,8,1,5,2,}
CD={4,6,8,9,1,3,5,6,7,9,}

Let Pn be the integer formed by concatenating the first n elements of PD (Cn is defined similarly for CD).
P10=2357248152
C10=4689135679

Let f(n) be the smallest positive integer that is a common superinteger of Pn and Cn.
For example, f(10)=2357246891352679, and f(100)mod1000000007=771661825.

Find f(10000)mod1000000007.

Write-up coming later

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