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.

Previous Showing 11-18 of 18 results.

A059582 First differences give digits of Pi = 3.1415926...

Original entry on oeis.org

1, 4, 5, 9, 10, 15, 24, 26, 32, 37, 40, 45, 53, 62, 69, 78, 81, 83, 86, 94, 98, 104, 106, 112, 116, 119, 122, 130, 133, 135, 142, 151, 156, 156, 158, 166, 174, 178, 179, 188, 195, 196, 202, 211, 214, 223, 232, 235, 242, 247, 248, 248, 253, 261, 263, 263, 272
Offset: 0

Views

Author

Rodolfo Kurchan, Feb 17 2001

Keywords

Comments

A more natural variant is given by A046974, the partial sums of the digits of Pi (A000796). Maybe the present version is motivated by the coincidence that the first four digits 1,4,5,9 are similar to the decimals .14159 of Pi. - M. F. Hasler, Jan 19 2015

Crossrefs

Programs

  • Maple
    Digits := 200: it := evalf(Pi, 200)/10: out := 1: for i from 1 to 200 do printf(`%d,`,out): out := out+floor(10*it): it := 10*it-floor(10*it): od:
  • Mathematica
    Accumulate[Join[{1},RealDigits[Pi,10,60][[1]]]] (* Harvey P. Dale, Jan 18 2015 *)
  • PARI
    { default(realprecision, 2080); a=1; x=Pi/10; for (n=0, 2000, d=floor(x); x=(x-d)*10; write("b059582.txt", n, " ", a+=d)); } \\ Harry J. Smith, Jun 28 2009

Extensions

More terms from James Sellers, Feb 19 2001

A098934 Numbers n such that the sum of the first n digits of Pi are divisible by n.

Original entry on oeis.org

1, 2, 9, 11, 16
Offset: 1

Views

Author

Anne M. Donovan (anned3005(AT)aol.com), Oct 20 2004

Keywords

Comments

For large n, A046974(n-1)/n is very close to 4.5, so is never an integer. - David Wasserman, Feb 27 2008

Examples

			a[1] = 1 since 3 is divisible by 1.
a[2] = 2 since 3 + 1 = 4 is divisible by 2.
a[3] != 3 since 3 + 1 + 4 = 8 is not divisible by 3.
		

Crossrefs

Cf. A046974.

Programs

  • Mathematica
    $MaxPrecision = 2500000; pd = RealDigits[N[Pi, 2000000]][[1]]; s = 0; Do[s = s + pd[[n]]; If[ Mod[s, n] == 0, Print[n]], {n, 2000000}] (* Robert G. Wilson v, Oct 21 2004 *)
    Module[{nn=20,pid},pid=RealDigits[Pi,10,nn][[1]];Select[Range[nn],Mod[Total[Take[pid,#]],#]==0&]] (* Harvey P. Dale, Aug 30 2025 *)

A099540 Sum of the first n digits of log(Pi)=1.14472988584940017...

Original entry on oeis.org

1, 2, 6, 10, 17, 19, 28, 36, 44, 49, 57, 61, 70, 74, 74, 74, 75, 82, 86, 87, 91, 94, 98, 100, 107, 110, 115, 116, 119, 124, 127, 127, 132, 140, 147, 148, 149, 155, 159, 166, 168, 177, 181, 189, 190, 192, 201, 202, 207, 210, 211, 212, 217, 224, 225, 230, 231, 234
Offset: 1

Views

Author

Mark Hudson (mrmarkhudson(AT)hotmail.com), Oct 25 2004

Keywords

Examples

			log(Pi)=1.14472988584940017... which gives the sums 1, 1+1, 1+1+4, 1+1+4+4, 1+1+4+4+7,... leading to the terms 1, 2, 6, 10, 17,...
		

Crossrefs

Similarly constructed sequences A099534-A099539, A093084, A039918, A046974, A046975. Digits of log(Pi)=A053510.

Programs

  • Mathematica
    Accumulate[RealDigits[Log[Pi],10,120][[1]]] (* Harvey P. Dale, Aug 14 2018 *)

A131660 Positions at which the sum of the digits of e up to that point equals the sum of the digits of Pi up to that point.

Original entry on oeis.org

218, 241, 264, 269, 280, 287, 354, 1159, 1836, 1871, 1872, 1886, 1891, 1892, 1914, 5023, 5026, 5039, 9165, 9170, 9171, 9180, 15166, 17909, 91192, 91194, 91277, 91289, 91290, 91293, 92029, 92031, 92033, 92038, 93913, 93927, 93928, 97369, 97839
Offset: 1

Views

Author

Sergio Pimentel, Sep 13 2007

Keywords

Comments

Numbers n such that A046974(n) = A046975(n). - Robert G. Wilson v, Sep 16 2007

Examples

			a(1)=218 because the sum of the first 218 digits of e (including the initial 2) equals 987. That is the same result for the first 218 digits of Pi (including the initial 3).
		

Crossrefs

Programs

  • Mathematica
    de = First@ RealDigits[E, 10, 10^5]; dse = 0; dpi = First@ RealDigits[Pi, 10, 10^5]; dspi = 0; lst = {}; Do[ dse = dse + de[[n]]; dspi = dspi + dpi[[n]]; If[dse == dspi, AppendTo[lst, n]; Print@n], {n, 10^5}] (* Robert G. Wilson v, Sep 16 2007 *)
    Module[{nn=100000,ed,pd},ed=Accumulate[RealDigits[E,10,nn][[1]]];pd= Accumulate[ RealDigits[Pi,10,nn][[1]]];Flatten[Position[Thread[ {ed,pd}], ?(#[[1]]==#[[2]]&),{1},Heads->False]]] (* _Harvey P. Dale, Feb 18 2015 *)

Extensions

More terms from Robert G. Wilson v, Sep 16 2007
a(6) corrected by N. J. A. Sloane, Nov 23 2007

A133213 Prime partial sums of digits of decimal expansion of pi (A000796).

Original entry on oeis.org

3, 23, 31, 61, 97, 103, 157, 173, 241, 271, 313, 421, 433, 443, 449, 491, 503, 503, 523, 541, 541, 547, 557, 607, 617, 617, 647, 673, 673, 733, 757, 773, 787, 811, 821, 823, 887, 907, 911, 929, 977, 983, 991, 997, 1019, 1103, 1123, 1123, 1171, 1201, 1201
Offset: 1

Views

Author

Lekraj Beedassy, Dec 29 2007

Keywords

Comments

Prime terms of A046974.

Crossrefs

Programs

  • Mathematica
    Select[Accumulate[First[RealDigits[N[ \[Pi],500]]]],PrimeQ] [Harvey Dale]

Extensions

Terms a(10)-a(16) added by Jason G. Wurtzel, Aug 18 2010
Further terms from Harvey P. Dale, Aug 21 2010

A276111 Decimal expansion of Pi truncated to numbers such that the partial sums of the decimal digits are perfect squares.

Original entry on oeis.org

31, 3141, 3141592, 314159265, 31415926535897932384626433
Offset: 1

Views

Author

Michel Lagneau, Aug 18 2016

Keywords

Comments

Members of A011545.
a(6)= 3141592653...647093 contains 123 digits;
a(7)= 3141592653...128475 contains 226 digits;
a(8)= 3141592653...786783 contains 238 digits;
a(9)= 3141592653...789259 contains 357 digits;
a(10)= 3141592653...892590 contains 358 digits;
a(11)= 3141592653...261179 contains 441 digits.
The corresponding partial sums are 4, 9, 25, 36, 121,...(subsequence of A046974).
The corresponding square roots are in the following sequence b(n): 2, 3, 5, 6, 11, 24, 32, 33, 40, 44, 52, 62, 65, 66, 89, 100, 101, 110, 115, 116, 121, 135, 142, 144, 159, 161, 173, 177, 187, 190, 196, 197,...
The primes in b(n) are 2, 3, 5, 11, 89, 101, 173, 197, 227,...
The squares in b(n) are 100, 121, 144, 196, 256, 289, 324, 729, 784,..

Crossrefs

Programs

A076819 Least position m > n in the decimal expansion of Pi=3.1415... such that the sum of all digits at positions < n is not greater than the sum of all digits at positions > n and <= m.

Original entry on oeis.org

3, 5, 6, 6, 10, 12, 13, 14, 15, 18, 20, 24, 27, 31, 34, 35, 36, 38, 40, 42, 43, 45, 46, 47, 48, 52, 54, 56, 57, 59, 63, 63, 63, 67, 70, 73, 75, 76, 80, 81, 82, 85, 88, 90, 97, 100, 101, 102, 105, 105, 106, 109, 110, 112, 114, 119, 121, 123, 126, 128, 130, 132, 135
Offset: 2

Views

Author

Reinhard Zumkeller, Nov 17 2002

Keywords

Comments

For n > 1: A046974(n-1) <= A046974(a(n)) - A046974(n) and A046974(n-1) > A046974(a(n)-1) - A046974(n).

Examples

			n=6: 3+1+4+1+5 <= 2+6+5+3 and 3+1+4+1+5 > 2+6+5; '31415[9]26535897...'.
		

Crossrefs

Cf. A000796.

A306389 Partial sums of (k-th digit of decimal expansion of Pi multiplied by (-1)^k).

Original entry on oeis.org

-3, -2, -6, -5, -10, -1, -3, 3, -2, 1, -4, 4, -5, 2, -7, -4, -6, -3, -11, -7, -13, -11, -17, -13, -16, -13, -21, -18, -20, -13, -22, -17, -17, -15, -23, -15, -19, -18, -27, -20, -21, -15, -24, -21, -30, -21, -24, -17, -22, -21, -21, -16, -24, -22, -22, -13, -20, -16, -25, -21, -25, -20, -29, -27, -30, -30, -37, -29, -30, -24, -28
Offset: 1

Views

Author

Luca Petrone, Feb 12 2019

Keywords

Comments

a(n) > 0 for n = 8, 10, 12, 14, 16124, 16126, ... and a(n) = 0 for n = 16120, 16161, 16937, ... - Michel Marcus, Feb 13 2019

Crossrefs

Programs

  • Mathematica
    Accumulate@ MapIndexed[(-1)^First[#2]*#1 &, First@ RealDigits[Pi, 10, 71]] (* Michael De Vlieger, Feb 15 2019 *)

Formula

a(n) = Sum_{k=1..n} (-1)^k*A000796(k).
a(n) = Sum_{k=1..floor(n/2)} A099817(k) - Sum_{k=1..floor((n+1)/2)} A099816(k). - Michel Marcus, Feb 16 2019
Previous Showing 11-18 of 18 results.