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.

Showing 1-3 of 3 results.

A300397 a(n) = number of primes that end in 1 among the first 10^n primes.

Original entry on oeis.org

1, 24, 245, 2484, 24967, 249934, 2499755, 24999435, 249997579, 2499995131, 24999983109, 249999976990
Offset: 1

Views

Author

G. L. Honaker, Jr., Mar 05 2018

Keywords

Examples

			a(1) = 1 because the first 10 primes are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, among which there is only one prime ending in 1.

Crossrefs

Cf. A006988, A030430, A185705, A300398, A300399, A300400.

Programs

  • PARI
    a(n) = #select(x->((x % 10) == 1), primes(10^n)); \\ Michel Marcus, Mar 07 2018

Formula

a(n) = A185705(A006988(n)). - Michel Marcus, Mar 20 2018

Extensions

a(3)-a(8) from Chuck Gaydos
a(9) from Jon E. Schoenfield, Mar 20 2018
a(10)-a(12) from Giovanni Resta, Mar 27 2018

A300399 a(n) = number of primes that end in 7 among the first 10^n primes.

Original entry on oeis.org

2, 24, 254, 2508, 25015, 250014, 2500283, 25000402, 250002505, 2500005319, 25000014226, 250000051446
Offset: 1

Views

Author

G. L. Honaker, Jr., Mar 05 2018

Keywords

Examples

			a(1) = 2 because the first 10 primes are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, among which there are two primes ending in 7.

Crossrefs

Cf. A006988, A030432, A185714, A300397, A300398, A300400.

Programs

  • PARI
    a(n) = #select(x->((x % 10) == 7), primes(10^n)); \\ Michel Marcus, Mar 07 2018

Formula

a(n) = A185714(A006988(n)). - Michel Marcus, Mar 20 2018

Extensions

a(3)-a(8) from Chuck Gaydos
a(9) from Jon E. Schoenfield, Mar 20 2018
a(10)-a(12) from Giovanni Resta, Mar 27 2018

A300400 a(n) = number of primes that end in 9 among the first 10^n primes.

Original entry on oeis.org

2, 24, 246, 2491, 25009, 249940, 2499751, 25000026, 249997694, 2499999305, 24999974939, 249999962302
Offset: 1

Views

Author

G. L. Honaker, Jr., Mar 05 2018

Keywords

Examples

			a(1) = 2 because the first 10 primes are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, among which there are two primes ending in 9.

Links

Crossrefs

Cf. A006988, A030433, A185715, A300397, A300398, A300399.

Programs

  • PARI
    a(n) = #select(x->((x % 10) == 9), primes(10^n)); \\ Michel Marcus, Mar 07 2018

Formula

a(n) = A185715(A006988(n)). - Michel Marcus, Mar 20 2018

Extensions

a(3)-a(8) from Chuck Gaydos
a(9) from Jon E. Schoenfield, Mar 20 2018
a(10)-a(12) from Giovanni Resta, Mar 27 2018
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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