A008829 Smallest number a(n) formed from consecutive sequences of digits of Pi and satisfying a(n) > a(n-1); first 3 is omitted.

1, 4, 15, 92, 653, 5897, 9323, 84626, 433832, 795028, 841971, 6939937, 51058209, 74944592, 307816406, 2862089986, 28034825342, 1170679821480, 8651328230664, 70938446095505, 82231725359408, 128481117450284, 1027019385211055

Offset: 1

Author

N. J. A. Sloane. This sequence appeared in the 1973 "Handbook", but was then dropped from the database. Resubmitted by Victor H. Auerbach (vhambler(AT)voicenet.com). Entry revised by N. J. A. Sloane, Jun 11 2012

Keywords

• nonn
• base

Comments

Terms are not permitted to start with a 0, so when this would otherwise occur the 0 must be included in the previous term, for example, a(18). - Sean A. Irvine, Apr 07 2018

References

• N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

Links

• Sean A. Irvine, Table of n, a(n) for n = 1..250

Crossrefs

Cf. A000796. Apart from the two initial terms equals A016062.

Programs

Mathematica

pi = Rest@ RealDigits[Pi, 10, 2500][[1]]; a[0] = 0; a[n_] := a[n] = Block[{k = 1}, While[ FromDigits[ Take[pi, {1, k}]] < a[n - 1], k++]; While[ pi[[k + 1]] == 0, k++]; b = FromDigits[Take[pi, {1, k}]]; pi = Drop[pi, k]; b]; Array[a, 50] (* Robert G. Wilson v, Apr 08 2018 *)

Extensions

a(19)-a(20) corrected and more terms from Sean A. Irvine, Apr 07 2018