A100414 -id:A100414 - cp's OEIS frontend

A100415 Numbers n such that n is R(n)-th nonprime number, where R(n) is the digit reversal of n (A018252(A004086(n))=n).

1, 64, 524, 534, 58725, 907538, 6264385, 9438088, 9596598, 27895162, 422984004, 548911025, 8804661048, 49640253574, 63899981216, 95138721219, 97895906839, 469449672154

Offset: 1

Farideh Firoozbakht, Dec 12 2004

n is in the sequence iff n is not prime and R(n)=n-pi(n). There is no further term up to 3670000000.

a(19) > 10^13. Up to that limit, this sequence contains all the numbers k such that R(k) = k - pi(k). - Giovanni Resta, Aug 08 2019

			548911025 is in the sequence because 548911025 is the 520118945th nonprime natural number.

Cf. A018252, A004086, A100413, A100414, A114926.

Do[s = FromDigits[Reverse[IntegerDigits[n]]]; If[ ! PrimeQ[n] && s == n - PrimePi[n], Print[n]], {n, 548911025}]

a(13)-a(18) from Giovanni Resta, Aug 08 2019

A246808 Palindromic terms of the sequence A245317.

Original entry on oeis.org

2112, 4803443084, 6992662996, 180461164081, 214591195412, 409473374904, 563715517365, 4163019339103614, 1050417996997140501

Offset: 1

Jahangeer Kholdi, Sep 17 2014

For each n, A100414(n).reversal(A100414(n)) is in the sequence, where dot denotes concatenation. What is the first term of the sequence which is not of the above form?
a(9) <= 253385633342243336583352 and a(10) <= 661494322636636223494166.
a(9) = A245317(997140501) = 1050417996997140501 is the smallest term of the sequence which is not of the form A100414(n).reversal(A100414(n)).  253385633342243336583352 and 661494322636636223494166 are two consecutive terms of the sequence. - Farideh Firoozbakht, Sep 23 2014

Cf. A002808, A004086, A100414, A245317.

h[n_]:=If[!PrimeQ[n],FromDigits[Flatten[{IntegerDigits[n],IntegerDigits[n-PrimePi[n]-1]}]]];Do[a=h[n];If[!PrimeQ[n]&&FromDigits[Reverse[IntegerDigits[a]]]==a,Print[a]],{n,100000000}]

For n<9, a(n) = A100414(n).reversal(A100414(n)).

a(9) from Farideh Firoozbakht, Sep 23 2014

cp's OEIS Frontend

A100415 Numbers n such that n is R(n)-th nonprime number, where R(n) is the digit reversal of n (A018252(A004086(n))=n).

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