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.

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A080172 Final digit of n-th Mersenne prime A000668(n).

Original entry on oeis.org

3, 7, 1, 7, 1, 1, 7, 7, 1, 1, 7, 7, 1, 7, 7, 7, 1, 1, 1, 7, 1, 1, 1, 1, 1, 1, 1, 7, 7, 1, 7, 7, 1, 7, 1, 1, 1, 1, 1, 7, 7, 7, 1, 1, 7, 1, 1, 1
Offset: 1

Views

Author

Mark Dowdeswell, Feb 04 2003

Keywords

Comments

Distribution of final digit for Mersenne primes appears (naturally) to be different from distribution for regular primes. Unconfirmed 49th, 50th and 51st digits in sequence are 1, 1, 1 (awaiting confirmation of 49th, 50th and 51st Mersenne primes).

References

  • G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers. 3rd ed., Oxford Univ. Press, 1954, p. 16.

Crossrefs

Programs

  • Maple
    (Maple code from N. J. A. Sloane) # let s1 := list of terms in A000043
    f:=n->if n mod 4 = 0 then 4 else n mod 4; fi; map(x->2^f(x)-1,s1);
  • Mathematica
    Mod[2^MersennePrimeExponent[Range[48]]-1,10] (* Harvey P. Dale, Aug 09 2023; updated by Mark Dowdeswell, Sep 16 2024 *)

Extensions

Updated by N. J. A. Sloane, Apr 01 2008
a(40)-a(47) from Ivan Panchenko, Apr 11 2018
a(48) from Mark Dowdeswell, Sep 16 2024

A211890 Triangle read by rows, where row n starts with n-th prime, followed by n primes in arithmetic progression; T(0,0) = 1 by convention.

Original entry on oeis.org

1, 2, 3, 3, 5, 7, 5, 11, 17, 23, 7, 37, 67, 97, 127, 11, 71, 131, 191, 251, 311, 13, 244243, 488473, 732703, 976933, 1221163, 1465393, 17, 6947, 13877, 20807, 27737, 34667, 41597, 48527, 19, 546859, 1093699, 1640539, 2187379, 2734219, 3281059, 3827899
Offset: 0

Views

Author

Reinhard Zumkeller, Jul 13 2012

Keywords

Comments

T(n,0) = A000040(n) and T(n,k+1) - T(n,k) = A211889(n), 0 <= k < n.

Examples

			First 9 rows of triangle:
0:  1
1:  2 3
2:  3 5 7
3:  5 11 17 23
4:  7 37 67 97 127
5:  11 71 131 191 251 311
6:  13 244243 488473 732703 976933 1221163 1465393
7:  17 6947 13877 20807 27737 34667 41597 48527
8:  19 546859 1093699 1640539 2187379 2734219 3281059 3827899 4374739
		

Crossrefs

Programs

  • Haskell
    a211890 n k = a211890_tabl !! n !! k
    a211890_row n = a211890_tabl !! n
    a211890_tabl = zipWith3 (\p k row -> map ((+ p) . (* k)) row)
                            a008578_list (0 : a211889_list) a002262_tabl

A039710 a(n) = n-th prime modulo 12.

Original entry on oeis.org

2, 3, 5, 7, 11, 1, 5, 7, 11, 5, 7, 1, 5, 7, 11, 5, 11, 1, 7, 11, 1, 7, 11, 5, 1, 5, 7, 11, 1, 5, 7, 11, 5, 7, 5, 7, 1, 7, 11, 5, 11, 1, 11, 1, 5, 7, 7, 7, 11, 1, 5, 11, 1, 11, 5, 11, 5, 7, 1, 5, 7, 5, 7, 11, 1, 5, 7, 1, 11, 1, 5, 11, 7, 1, 7, 11, 5, 1, 5, 1, 11
Offset: 1

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Author

Keywords

Crossrefs

Programs

Formula

Sum_k={1..n} a(k) ~ 6*n. - Amiram Eldar, Dec 11 2024

A039711 a(n) = n-th prime modulo 13.

Original entry on oeis.org

2, 3, 5, 7, 11, 0, 4, 6, 10, 3, 5, 11, 2, 4, 8, 1, 7, 9, 2, 6, 8, 1, 5, 11, 6, 10, 12, 3, 5, 9, 10, 1, 7, 9, 6, 8, 1, 7, 11, 4, 10, 12, 9, 11, 2, 4, 3, 2, 6, 8, 12, 5, 7, 4, 10, 3, 9, 11, 4, 8, 10, 7, 8, 12, 1, 5, 6, 12, 9, 11, 2, 8, 3, 9, 2, 6, 12, 7, 11, 6
Offset: 1

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Author

Keywords

Crossrefs

Programs

Formula

Sum_k={1..n} a(k) ~ (13/2)*n. - Amiram Eldar, Dec 11 2024

A039712 a(n) = n-th prime modulo 14.

Original entry on oeis.org

2, 3, 5, 7, 11, 13, 3, 5, 9, 1, 3, 9, 13, 1, 5, 11, 3, 5, 11, 1, 3, 9, 13, 5, 13, 3, 5, 9, 11, 1, 1, 5, 11, 13, 9, 11, 3, 9, 13, 5, 11, 13, 9, 11, 1, 3, 1, 13, 3, 5, 9, 1, 3, 13, 5, 11, 3, 5, 11, 1, 3, 13, 13, 3, 5, 9, 9, 1, 11, 13, 3, 9, 3, 9, 1, 5, 11, 5, 9
Offset: 1

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Author

Keywords

Crossrefs

Programs

Formula

Sum_k={1..n} a(k) ~ 7*n. - Amiram Eldar, Dec 12 2024

A110923 Final two digits of prime(n), with leading zero omitted.

Original entry on oeis.org

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 1, 3, 7, 9, 13, 27, 31, 37, 39, 49, 51, 57, 63, 67, 73, 79, 81, 91, 93, 97, 99, 11, 23, 27, 29, 33, 39, 41, 51, 57, 63, 69, 71, 77, 81, 83, 93, 7, 11, 13, 17, 31, 37
Offset: 1

Views

Author

Paolo P. Lava, Sep 23 2005

Keywords

Comments

Primes modulo 100.

Crossrefs

Programs

Formula

Sum_k={1..n} a(k) ~ 50*n. - Amiram Eldar, Dec 13 2024

Extensions

Edited, corrected and extended by Ray Chandler, Oct 01 2005

A166499 Concatenation of the rightmost digit of the n-th prime and the leftmost digit of the (n+1)th prime.

Original entry on oeis.org

23, 35, 57, 71, 11, 31, 71, 92, 32, 93, 13, 74, 14, 34, 75, 35, 96, 16, 77, 17, 37, 98, 38, 99, 71, 11, 31, 71, 91, 31, 71, 11, 71, 91, 91, 11, 71, 31, 71, 31, 91, 11, 11, 31, 71, 92, 12, 32, 72, 92, 32, 92, 12, 12, 72, 32, 92, 12, 72, 12, 32, 33, 73, 13, 33, 73, 13, 73, 73
Offset: 1

Views

Author

Zak Seidov, Oct 15 2009

Keywords

Comments

This is the comma transform of the primes (see A367360).

Crossrefs

Programs

  • Maple
    a:= n-> parse(cat(""||(ithprime(n))[-1],""||(ithprime(n+1))[1])):
    seq(a(n), n=1..99);  # Alois P. Heinz, Nov 22 2023
  • Mathematica
    With[{nmax=100},Map[10Mod[#[[1]],10]+IntegerDigits[#[[2]]][[1]]&,Partition[Prime[Range[nmax+1]],2,1]]] (* Paolo Xausa, Nov 24 2023 *)

Formula

a(n) = 10 * A007652(n) + A077648(n+1). - Alois P. Heinz, Nov 23 2023

A039713 a(n) = n-th prime modulo 15.

Original entry on oeis.org

2, 3, 5, 7, 11, 13, 2, 4, 8, 14, 1, 7, 11, 13, 2, 8, 14, 1, 7, 11, 13, 4, 8, 14, 7, 11, 13, 2, 4, 8, 7, 11, 2, 4, 14, 1, 7, 13, 2, 8, 14, 1, 11, 13, 2, 4, 1, 13, 2, 4, 8, 14, 1, 11, 2, 8, 14, 1, 7, 11, 13, 8, 7, 11, 13, 2, 1, 7, 2, 4, 8, 14, 7, 13, 4, 8, 14, 7
Offset: 1

Views

Author

Keywords

Crossrefs

Programs

Formula

Sum_k={1..n} a(k) ~ (15/2)*n. - Amiram Eldar, Dec 12 2024

A039714 a(n) = n-th prime modulo 16.

Original entry on oeis.org

2, 3, 5, 7, 11, 13, 1, 3, 7, 13, 15, 5, 9, 11, 15, 5, 11, 13, 3, 7, 9, 15, 3, 9, 1, 5, 7, 11, 13, 1, 15, 3, 9, 11, 5, 7, 13, 3, 7, 13, 3, 5, 15, 1, 5, 7, 3, 15, 3, 5, 9, 15, 1, 11, 1, 7, 13, 15, 5, 9, 11, 5, 3, 7, 9, 13, 11, 1, 11, 13, 1, 7, 15, 5, 11, 15, 5
Offset: 1

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Author

Keywords

Crossrefs

Programs

Formula

Sum_k={1..n} a(k) ~ 8*n. - Amiram Eldar, Dec 12 2024

A072003 10's complement of final digit of n-th prime.

Original entry on oeis.org

8, 7, 5, 3, 9, 7, 3, 1, 7, 1, 9, 3, 9, 7, 3, 7, 1, 9, 3, 9, 7, 1, 7, 1, 3, 9, 7, 3, 1, 7, 3, 9, 3, 1, 1, 9, 3, 7, 3, 7, 1, 9, 9, 7, 3, 1, 9, 7, 3, 1, 7, 1, 9, 9, 3, 7, 1, 9, 3, 9, 7, 7, 3, 9, 7, 3, 9, 3, 3, 1, 7, 1, 3, 7, 1, 7, 1, 3, 9, 1, 1, 9, 9, 7, 1, 7, 1, 3, 9, 7, 3, 1, 3, 9, 1, 7, 1, 9, 7, 9, 3, 3, 7, 1, 9
Offset: 1

Views

Author

Roger L. Bagula, Jun 18 2002

Keywords

Crossrefs

Cf. A007652.

Programs

  • Mathematica
    a[n_] := 10-Mod[Prime[n], 10];
    Table[ a[n], {n, 1, 105}]

Formula

a(n) = 10 - (prime(n) mod 10).
A007652(n) + a(n) = 10.

Extensions

Edited by N. J. A. Sloane and Robert G. Wilson v, Jun 20 2002
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