cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A228520 a(n) is the smallest number such that if x >= a(n), then pi^*(x) - pi^*(x/2) >= n, where pi^*(x) is the number of terms of A050376 <= x.

Original entry on oeis.org

2, 3, 11, 16, 23, 41, 47, 59, 67, 71, 79, 101, 107, 109, 127, 149, 167, 169, 179, 181, 227, 229, 233, 239, 256, 263, 269, 281, 283, 307, 347, 349, 359, 367, 373, 401, 409, 419, 431, 433, 439, 461, 487, 491, 521, 569, 587, 593, 599, 601, 607, 617, 641, 643, 647
Offset: 1

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Author

Vladimir Shevelev, Aug 24 2013

Keywords

Comments

The sequence is a Fermi-Dirac analog of Ramanujan numbers (A104272), since terms of A050376 play a role of primes in Fermi-Dirac arithmetic (see comments in A050376).

Crossrefs

Cf. A104272.

Formula

a(n)<= R_n, where R_n is the n-th Ramanujan number (A104272); a(n)~A000040(2*n) as n goes to infinity.

Extensions

More terms from Peter J. C. Moses