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 1-4 of 4 results.

A077188 a(n) = A077186(n)/prime(n).

Original entry on oeis.org

0, 4107, 0, 1763664903, 11, 949665717
Offset: 1

Views

Author

Amarnath Murthy, Nov 01 2002

Keywords

Comments

Next terms are known but too large to include here.
a(5) = 11 is the only example of the form a(n) = prime(n)

Examples

			a(5) = 11 = 121/11.

Crossrefs

Cf. A077180, A077181, A077182, A077183, A077184, A077186, A077187.

Extensions

Edited by Max Alekseyev, Sep 14 2009

A077189 Smallest concatenation 123...(k-1) k (k-1)...321 (a concatenation of natural numbers from 1 to k and back to 1) that is a multiple of 2n-1, or 0 if no such number exists.

Original entry on oeis.org

1, 12321, 0, 12345654321, 12321, 121, 12345654321, 0
Offset: 1

Views

Author

Amarnath Murthy, Nov 01 2002

Keywords

Comments

a(5k+3) = 0. Are there any other values of n such that a(n) = 0?
The next value, 2n-1 = 17, has k = 109, for a total of 435 digits and is too large to include. - Franklin T. Adams-Watters, Jun 02 2006

Examples

			a(5) = 12321 is a multiple of 9.

Links

Crossrefs

Cf. A077180, A077181, A077182, A077183, A077184, A077186, A077188, A077190.
Cf. A120008.

Extensions

More terms from Franklin T. Adams-Watters, Jun 02 2006

A077187 Smallest k such that the concatenation 123...(k-1) k (k-1)...321 ( a concatenation of natural numbers from 1 to k and back to 1) is a multiple of prime(n), or 0 if no such number exists.

Original entry on oeis.org

0, 3, 0, 6, 2, 6, 109, 103, 100001, 1006, 17, 3, 5, 103, 1000002, 100012, 1019, 1002, 1001, 16, 8, 105, 1036, 104, 1002, 4, 100000000009, 100004, 52, 156, 10000000012, 1062, 8, 1002, 28, 102, 1011, 1000062, 30, 10001, 118, 52, 43, 10058, 34, 47
Offset: 1

Views

Author

Amarnath Murthy, Nov 01 2002

Keywords

Examples

			a(5) = 2 as 121 is a multiple of 11.

Crossrefs

Cf. A077180, A077181, A077182, A077183, A077184, A077186, A077188.

Programs

  • PARI
    { a(n) = local(p,c10,z,u,v,l,k,lk,L,q); p=prime(n); c10=Mod(10,p); z=znorder(c10); u=v=Mod(1,p); l=1; k=2; L=List(); while(1, lk=1+log(k+0.1)\log(10); if(k==10^(lk-1), L=List()); if( u*c10^(l+lk)+k*c10^l+v==0, return(k)); q=0; t=[u,v,k%p,l%z]; for(j=1,#L,if(t==L[j], q=1+#L-j)); if(q, k+=((10^lk-1-k)\q)*q; L=List(), listput(L,t)); u=u*c10^lk+k; v+=k*c10^l; l+=lk; k++) } \\ Max Alekseyev, Sep 11 2009

Extensions

3 more terms from Erich Friedman, Aug 08 2005
Extended by Max Alekseyev, Sep 11 2009

A077190 a(n) = A077189(n)/(2n-1).

Original entry on oeis.org

1, 4107, 0, 1763664903, 1369, 11, 949665717, 0
Offset: 1

Views

Author

Amarnath Murthy, Nov 01 2002

Keywords

Comments

a(5k+3) = 0. Are there any other values of n so that a(n) = 0?

Examples

			a(5) = 12321/9 = 1369.

Links

Crossrefs

Cf. A077180, A077181, A077182, A077183, A077184, A077186, A077188, A077189.

Extensions

a(7)-a(8) from Jinyuan Wang, Mar 04 2020
Showing 1-4 of 4 results.

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

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