A121280 Position where concatenate(1,...,n) occurs for the first time in the decimals of Pi (where 3, 1, 4,... are at position 0, 1, 2,...).

1, 148, 1924, 13807, 49702, 2458885, 9470344, 186557266, 523551502, 191278379839, 4368196101671

Offset

1,2

Comments

This sequence uses the same convention for the "position" as sequences A035117, A050279 - A050287, A048940, A096755 - A096763, while A068987(n) = a(n)+1 counts the positions of 3,1,4,.... as 1,2,3,... - M. F. Hasler, Mar 18 2017

a(10) > 2*10^9. - M. F. Hasler, Apr 13 2019

a(12) > 22*10^12. - Dmitry Petukhov, Jan 29 2020

Links

Table of n, a(n) for n=1..11.

Dave G. Andersen, The Pi-Search Page

Subidiom.com, Irrational numbers search engine: π = 3.14159...

Peter Trüb, 22.4 trillion digits of pi

Formula

a(n) = A068987(n) - 1.

Crossrefs

First occurrence of n times the same digit: A035117 (n '1's), A050281 (n '2's), A050282, A050283, A050284, A050286, A050287, A048940 (n '9's).

First occurrence of exactly n times the same digit: A096755 (exactly n '1's), A096756, A096757, A096758, A096759, A096760, A096761, A096762, A096763 (exactly n '9's), A050279 (exactly n '0's).

Cf. A176341: first occurrence of n; A121280 = A068987 - 1: first occurrence of concatenate(1,...,n).

Cf. A000796: Decimal expansion (or digits) of Pi.

Sequence in context: A186894 A233727 A178264 * A338970 A224260 A223916

Adjacent sequences: A121277 A121278 A121279 * A121281 A121282 A121283

Keyword

nonn,base,more

Author

Alexander R. Povolotsky, Nov 03 2007

Extensions

New definition and cross-references from M. F. Hasler, Mar 18 2017

Additional term a(9), using subidiom search engine, from M. F. Hasler, Apr 13 2019

a(10)-a(11) from Dmitry Petukhov, Jan 16 2020

Status

approved