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.

A014950 Numbers m such that m divides 10^m - 1.

Original entry on oeis.org

1, 3, 9, 27, 81, 111, 243, 333, 729, 999, 2187, 2997, 4107, 6561, 8991, 12321, 13203, 19683, 20439, 26973, 36963, 39609, 59049, 61317, 80919, 110889, 118827, 151959, 177147, 183951, 242757, 332667, 356481, 455877, 488511, 531441, 551853, 728271
Offset: 1

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Author

Keywords

Comments

Also, m such that m | R(m) = A002275(m). - Lekraj Beedassy, Mar 25 2005
For n > 1, 3 divides a(n). If m is in the sequence and d divides m then for each positive integer k, d^k*m is in the sequence. So if m is in the sequence then m^k is in the sequence for each positive integer k. In particular, 3^k is in this sequence for all k. - Farideh Firoozbakht, Apr 14 2010
Numbers m such that m divides s(m), where s(1) = 1, s(k) = s(k-1) + k*10^(k-1).
Number of terms <= 10^k, beginning with k = 0: 1, 3, 5, 10, 15, 25, 41, 68, 108, 178, 291, ... - Robert G. Wilson v, Nov 30 2013
Numbers m such that m divides A033713(m). - Hans Havermann, Jan 25 2014

References

  • J. D. E. Konhauser et al., Which Way Did The Bicycle Go? Problem 80 pp. 26; 133, Dolciani Math. Exp., No. 18, MAA, Washington DC, 1996.

Crossrefs

Programs

Formula

Solutions to 10^m == 1 (mod m). - Vladeta Jovovic

Extensions

More terms from Vladeta Jovovic, Dec 18 2001
More terms from Larry Reeves (larryr(AT)acm.org), Jan 06 2005
Edited by Max Alekseyev, May 20 2011

A066364 Prime divisors of solutions to 10^n == 1 (mod n).

Original entry on oeis.org

3, 37, 163, 757, 1999, 5477, 8803, 9397, 13627, 15649, 36187, 40879, 62597, 106277, 147853, 161839, 215893, 231643, 281683, 295759, 313471, 333667, 338293, 478243, 490573, 607837, 647357, 743933, 988643, 1014877, 1056241, 1168711, 1353173, 1390757, 1487867, 1519591, 1627523, 1835083, 1912969, 2028119, 2029759, 2064529
Offset: 1

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Author

Vladeta Jovovic, Dec 21 2001

Keywords

Examples

			10^27-1 = 3^5*37*757*333667*440334654777631 is a solution to the congruence.
		

Crossrefs

Programs

  • Mathematica
    fQ[p_] := Block[{fi = First@# & /@ FactorInteger[ MultiplicativeOrder[ 10, p]]}, Union[ MemberQ[ lst, #] & /@ fi] == {True}]; k = 4; lst = {3}; While[k < 180000, If[ p = Prime@ k; fQ@ p, AppendTo[ lst, p]; Print@ p]; k++]; lst (* Robert G. Wilson v, Nov 30 2013 *)
  • PARI
    S=Set([3]); forprime(p=7,10^6, v=factorint(znorder(Mod(10,p)))[,1]; if(length(setintersect(S,Set(v)))==length(v), S=setunion(S,[p])) ); print(vecsort(eval(S))) \\ Max Alekseyev, Nov 16 2005

Formula

A prime p is a term iff all prime divisors of ord_p(10) are terms, where ord_p(10) is the order of 10 modulo p. - Max Alekseyev, Nov 16 2005

Extensions

Edited by Max Alekseyev, Nov 16 2005
Edited by Hans Havermann, Jul 11 2014

A171981 Smallest multiples from A129066 of primes from A171980.

Original entry on oeis.org

5, 75025, 9006076025, 332813125, 54036081025, 162108093025, 12304690625, 3662109765625, 1238325212525, 225150026875625, 8562180281412026525, 309581286250625, 15197626762525, 4520507828125, 2059936966552758203125
Offset: 1

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Author

Max Alekseyev, Jan 20 2010

Keywords

Comments

A129066 lists integers n such that n divides n-th Fibonacci number A000045(n) with multiples of 12 excluded, while A171980 lists possible prime divisors of elements of A129066 in the increasing order. This sequence lists smallest multiples from A129066 of primes from A171980.

Crossrefs

Formula

a(n) = min { A129066(m) : A171980(n)|A129066(m) }

A354027 Smallest k dividing 3^k + 4^k that have divisor A354026(n).

Original entry on oeis.org

7, 2653, 4941601, 236474833, 20930936750059, 4899815786803, 330219333283, 4455186224209, 9770481627816301, 351829430300299, 26064955344333473991073, 192144131632327, 3006539977771582357, 2059085249993107, 13468375028434716454309, 1753571527639980559, 2338095370082599813
Offset: 1

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Author

Max Alekseyev, May 15 2022

Keywords

Comments

Smallest term of A045584 divisible by prime A354026(n).

Crossrefs

Showing 1-4 of 4 results.