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.

A262369 A(n,k) is the n-th prime whose decimal expansion begins with the decimal expansion of k; square array A(n,k), n>=1, k>=1, read by antidiagonals.

Original entry on oeis.org

11, 2, 13, 3, 23, 17, 41, 31, 29, 19, 5, 43, 37, 211, 101, 61, 53, 47, 307, 223, 103, 7, 67, 59, 401, 311, 227, 107, 83, 71, 601, 503, 409, 313, 229, 109, 97, 89, 73, 607, 509, 419, 317, 233, 113, 101, 907, 809, 79, 613, 521, 421, 331, 239, 127
Offset: 1

Views

Author

Alois P. Heinz, Sep 20 2015

Keywords

Examples

			Square array A(n,k) begins:
:  11,   2,   3,  41,   5,  61,   7,  83, ...
:  13,  23,  31,  43,  53,  67,  71,  89, ...
:  17,  29,  37,  47,  59, 601,  73, 809, ...
:  19, 211, 307, 401, 503, 607,  79, 811, ...
: 101, 223, 311, 409, 509, 613, 701, 821, ...
: 103, 227, 313, 419, 521, 617, 709, 823, ...
: 107, 229, 317, 421, 523, 619, 719, 827, ...
: 109, 233, 331, 431, 541, 631, 727, 829, ...
		

Crossrefs

Row n=1 gives A018800.
Main diagonal gives A077345.

Programs

  • Maple
    u:= (h, t)-> select(isprime, [seq(h*10^t+k, k=0..10^t-1)]):
    A:= proc(n, k) local l, p;
          l:= proc() [] end; p:= proc() -1 end;
          while nops(l(k))
    				
  • Mathematica
    u[h_, t_] := Select[Table[h*10^t + k, {k, 0, 10^t - 1}], PrimeQ];
    A[n_, k_] := Module[{l, p}, l[] = {}; p[] = -1; While[Length[l[k]] < n, p[k] = p[k]+1; l[k] = Join[l[k], u[k, p[k]]]]; l[k][[n]]];
    Table[Table[A[n, 1+d-n], {n, 1, d}], {d, 1, 12}] // Flatten (* Jean-François Alcover, Dec 06 2019, from Maple *)

A077344 Triangle in which n-th row contains n smallest primes beginning with n.

Original entry on oeis.org

11, 2, 23, 3, 31, 37, 41, 43, 47, 401, 5, 53, 59, 503, 509, 61, 67, 601, 607, 613, 617, 7, 71, 73, 79, 701, 709, 719, 83, 89, 809, 811, 821, 823, 827, 829, 97, 907, 911, 919, 929, 937, 941, 947, 953, 101, 103, 107, 109, 1009, 1013, 1019, 1021, 1031, 1033
Offset: 1

Views

Author

Amarnath Murthy, Nov 05 2002

Keywords

Examples

			Triangle begins:
:  11;
:   2,  23;
:   3,  31,  37;
:  41,  43,  47, 401;
:   5,  53,  59, 503,  509;
:  61,  67, 601, 607,  613,  617;
:   7,  71,  73,  79,  701,  709,  719;
:  83,  89, 809, 811,  821,  823,  827,  829;
:  97, 907, 911, 919,  929,  937,  941,  947,  953;
: 101, 103, 107, 109, 1009, 1013, 1019, 1021, 1031, 1033;
		

Crossrefs

Extensions

More terms from Alois P. Heinz, Sep 30 2015

A262366 a(n) is the n-th prime whose binary expansion begins with the binary expansion of n.

Original entry on oeis.org

2, 5, 13, 67, 43, 107, 127, 263, 307, 349, 373, 773, 839, 907, 991, 1063, 1109, 1201, 1277, 1321, 2713, 2819, 2963, 3119, 3229, 3371, 3517, 3691, 3779, 3943, 4051, 4217, 8461, 8719, 8963, 9241, 9497, 9767, 10039, 10303, 10613, 10799, 11159, 11317, 11657, 11923
Offset: 1

Views

Author

Alois P. Heinz, Sep 20 2015

Keywords

Crossrefs

Main diagonal of A262365.
Cf. A077345.

Programs

  • Maple
    u:= (h, t)-> select(isprime, [seq(h*2^t+k, k=0..2^t-1)]):
    A:= proc(n, k) local l, p;
          l:= proc() [] end; p:= proc() -1 end;
          while nops(l(k)) A(n$2):
    seq(a(n), n=1..60);
Showing 1-3 of 3 results.