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 1-10 of 10 results.

A238697 Quotients connected with the Banach matchboxes problem: Sum_{i=1..prime(n)-7} 2^(i-1)*binomial(i+2,3)/prime(n) (case 3).

Original entry on oeis.org

0, 19, 197, 10481, 64027, 1980327, 259179061, 1257208799, 131286703021, 2756321451033, 12473384091267, 250290955437775, 21588599628845597, 1792050990708087027, 7763319803561678613, 620323392829436218475, 11365013042482773469559, 48487140450183407727097
Offset: 4

Views

Author

Vladimir Shevelev, Mar 03 2014

Keywords

Comments

See comment in A238693.

Crossrefs

Cf. A238693.

Programs

  • Mathematica
    Array[Sum[2^(i - 1)*Binomial[i + 2, 3]/#, {i, # - 7}] &@ Prime@ # &, 18, 4] (* Michael De Vlieger, Dec 06 2018 *)
  • PARI
    a(n) = sum(i=1, prime(n)-7, 2^(i-1)*binomial(i+2,3))/prime(n); \\ Michel Marcus, Dec 06 2018

Extensions

More terms from Peter J. C. Moses, Mar 03 2014

A238698 Quotients connected with the Banach matchboxes problem: Sum_{i=1..prime(n)-9} 2^(i-1)*binomial(i+3,4)/prime(n) (case 4).

Original entry on oeis.org

1, 27, 3599, 29157, 1362009, 271400395, 1469088801, 201573262419, 4910195172327, 23758960017789, 538608637491505, 54480012827209187, 5189654331623024397, 23446625614115858667, 2104894813684998321045, 41392675008326544152201, 182632116049323564469767
Offset: 5

Views

Author

Vladimir Shevelev, Mar 03 2014

Keywords

Comments

See comment in A238693.

Crossrefs

Programs

  • Mathematica
    k=4;(*case 4*)
    Table[Sum[2^(i-1)Binomial[i+k-1,k],{i,p-(2k+1)}]/p,{p,Prime[Range[k+1,20]]}] (* Peter J. C. Moses, Mar 04 2014 *)

Extensions

More terms from Peter J. C. Moses, Mar 03 2014

A238700 Quotients connected with the Banach matchboxes problem: Sum_{i=1..prime(n)-11} 2^(i-1)*binomial(i+4,5)/prime(n) (case 5).

Original entry on oeis.org

1, 625, 7451, 587687, 192856629, 1183808479, 220742818733, 6334029208601, 32973262995075, 853235644319439, 102411500363403805, 11294927679436544243, 53352132931526366997, 5415828333647578287211, 114722120087477391174007, 524320903831521291661817
Offset: 6

Views

Author

Vladimir Shevelev, Mar 03 2014

Keywords

Comments

See comment in A238693.

Crossrefs

Programs

  • Maple
    A238700:=n->sum(2^(i-1)*binomial(i+4,5)/ithprime(n), i=1..ithprime(n) - 11); seq(A238700(n), n=6..25); # Wesley Ivan Hurt, Mar 03 2014
  • Mathematica
    Table[Sum[2^(i - 1)*Binomial[i + 4, 5]/Prime[n], {i, Prime[n] - 11}], {n, 6, 25}] (* Wesley Ivan Hurt, Mar 03 2014 *)

Extensions

More terms from Peter J. C. Moses, Mar 03 2014

A239502 (Round(q^prime(n)) - 1)/prime(n), where q is the tribonacci constant (A058265).

Original entry on oeis.org

4, 10, 74, 212, 1856, 5618, 53114, 1630932, 5161442, 167427844, 1729192432, 5577731626, 58401766802, 2005139696964, 69737304018266, 228184540445268, 8043367476888770, 86866463049858250, 285815985033409648, 10225367934387562098, 111384745483589787826
Offset: 3

Views

Author

Keywords

Comments

For n>=3, round(q^prime(n)) == 1 (mod 2*prime(n)). Proof in Shevelev link. In particular, all terms are even.

Examples

			For n=3, q^5 = 21.049..., so a(3) = (21 - 1)/5 = 4.
		

Crossrefs

A239544 (Round(c^prime(n)) - 1)/prime(n), where c is the tetranacci constant (A086088).

Original entry on oeis.org

14, 124, 390, 4118, 13690, 156122, 6351030, 22074820, 948652694, 11818395344, 41868809842, 528803858638, 24052859078262, 1108257471317098, 3982717894786008, 185987895674303758, 2422894681885464596, 8755616404517667662, 414985190213435939298
Offset: 4

Views

Author

Keywords

Comments

For n>=4, round(c^prime(n)) == 1 (mod 2*prime(n)). Proof in Shevelev link. In particular, all terms are even.

Crossrefs

A239564 a(n) = (round(c^prime(n)) - 1)/prime(n), where c is the pentanacci constant (A103814).

Original entry on oeis.org

154, 504, 5758, 19912, 245714, 11251030, 40679232, 1967728552, 26525975822, 97753187576, 1335948880418, 68398141417510, 3547322151373882, 13260715720748120, 697034813138756392, 9825603574709578482, 36935066391752894480, 1970457739485406707872
Offset: 5

Views

Author

Keywords

Comments

For n>=5, round(c^prime(n)) == 1 (mod 2*prime(n)). Proof in Shevelev link. In particular, all terms are even.

Crossrefs

A239565 (Round(c^prime(n)) - 1)/prime(n), where c is the hexanacci constant (A118427).

Original entry on oeis.org

6702, 23594, 301738, 14576792, 53653610, 2738173594, 38254296398, 143514673148, 2032676550562, 109797468019174, 6007838407290514, 22863415355711030, 1267938526864061370, 18523200405015238420, 70884650213591098558, 3989789924439684599434
Offset: 7

Views

Author

Keywords

Comments

For n>=7, round(c^prime(n)) == 1 (mod 2*prime(n)). Proof in Shevelev link. In particular, all terms are even.

Crossrefs

A239566 (Round(c^prime(n)) - 1)/prime(n), where c is the heptanacci constant (A118428).

Original entry on oeis.org

7200, 25562, 332466, 16472758, 61145666, 3200477798, 45473543628, 172043098818, 2478186385762, 137291966046470, 7704742900338106, 29569459376703894, 1681851263230158754, 24987922624169214866, 96433670513455876108, 5566902760779797458210
Offset: 7

Views

Author

Keywords

Comments

For n>=7, round(c^prime(n)) == 1 (mod 2*prime(n)). Proof in Shevelev link. In particular, all terms are even.

Crossrefs

Formula

All roots of the equation x^7-x^6-x^5-x^4-x^3-x^2-x-1 = 0
are the following: c=1.9919641966050350211,
-0.78418701799584451319 +/- 0.36004972226381653409*i,
-0.24065633852269642508 + /- 0.84919699909267892575*i,
0.52886125821602342773 +/- 0.76534196109589443115*i.
Absolute values of all roots, except for septanacci constant c, are less than 1.
Conjecture. Absolute values of all roots of the equation x^n - x^(n-1) - ... -x - 1 = 0, except for n-bonacci constant c_n, are less than 1. If the conjecture is valid, then for sufficiently large k=k(n), for all m>=k, we have round(c_n^prime(m)) == 1 (mod 2*prime(m)) (cf. Shevelev link).

A238901 a(n) is the smallest k, 1<=k<=(p_n-3)/2, such that sum{i=1,...,p_n-2k-1} 2^(i-1) Binomial(k-1+i, k)/p_n is prime; a(n)=0, if such k does not exist.

Original entry on oeis.org

1, 1, 1, 6, 2, 5, 10, 1, 3, 11, 8, 13, 21, 5, 8, 29, 19, 19, 37, 0, 11, 11, 45, 42, 25, 11, 41, 7, 62, 39, 55, 70, 29, 60, 49, 24, 1, 0, 47, 73, 49, 78, 52, 11, 80, 80, 28, 32, 0, 92, 117, 112, 43, 102, 19, 97, 47, 38, 140, 51, 152, 44, 43, 141
Offset: 4

Views

Author

Vladimir Shevelev, Mar 06 2014

Keywords

Comments

Cf. comment in A238693.

Crossrefs

Extensions

More terms from Peter J. C. Moses, Mar 06 2014

A239640 a(n) is the smallest number such that for n-bonacci constant c_n satisfies round(c_n^prime(m)) == 1 (mod 2*p_m) for every m>=a(n).

Original entry on oeis.org

3, 3, 4, 5, 7, 7, 10, 13, 14, 14, 19, 23, 23, 31, 34, 34, 46, 50, 60, 65, 73, 79, 88, 92, 107, 113, 126, 139, 149, 168, 182, 198, 210, 227, 244, 265, 276, 292, 317, 340, 369, 384, 408, 436, 444, 480, 516, 540, 565, 606, 628, 669, 704, 735, 759, 810, 829, 895, 925
Offset: 2

Views

Author

Keywords

Comments

The n-bonacci constant is a unique root x_1>1 of the equation x^n-x^(n-1)-...-x-1=0. So, for n=2 we have Fibonacci constant phi or golden ratio (A001622); for n=3 we have tribonacci constant (A058265); for n=4 we have tetranacci constant (A086088), for n=5 (A103814), for n=6 (A118427), etc.

Examples

			Let n=2, then c_2 = phi (Fibonacci constant). We have round(c_2^2)=3 is not == 1 (mod 4), round(c_2^3)=4 is not == 1 (mod 6), while round(c_2^5)=11 == 1 (mod 10) and one can prove that for p>=5, we have round(c_2^p) == 1 (mod 2*p). Since 5=prime(3), then a(2)=3.
		

Crossrefs

Showing 1-10 of 10 results.