A071117 Numbers k such that the sum of the first k digits of the decimal expansion of e is prime.

1, 7, 8, 10, 18, 24, 38, 42, 52, 54, 64, 100, 107, 112, 113, 114, 135, 144, 145, 150, 151, 159, 162, 172, 177, 184, 189, 196, 197, 202, 213, 214, 223, 228, 230, 232, 238, 239, 240, 252, 255, 264, 267, 272, 278, 283, 302, 314, 315, 316, 332, 338, 366, 367, 374

Offset

1,2

Links

Table of n, a(n) for n=1..55.

Example

7 is a term because 2+7+1+8+2+8+1 = 29.

Mathematica

a = First[ RealDigits[ N[ E, 400]]]; Do[ If[ PrimeQ[Plus @@ Take[a, n]], Print[n]], {n, 1, 375}]

Crossrefs

Cf. A001113, A058938.

Sequence in context: A153972 A286420 A111064 * A054221 A377933 A195240

Adjacent sequences: A071114 A071115 A071116 * A071118 A071119 A071120

Keyword

base,easy,nonn

Author

Jason Earls, May 27 2002

Status

approved