A160130 - OEIS

%I #15 Apr 30 2023 17:29:54

%S 13,11,12,18,82,74,50,58,34,44,60,121,81,36,51,19,13,49,52,48,36,12,

%T 44,53,33,68,59,9,41,53,48,30,4,36,104,100,35,52,94,51,26,87,63,81,

%U 108,45,81,108,54,9,45,85,54,14,81,123,66,105,105,52,58,48,32

%N 2 x 2 inner (dot) products taken on corresponding digits in Pi and e.

%C Let pi(n) denote the n-th digit of Pi, and let e(n) denote the n-th digit of e. Define a(n) = pi(n)*e(n) + pi(n+1)*e(n+1).

%e The first two digits of Pi are 3 and 1; the first two digits of e are 2 and 7. Then a(1) = 3*2 + 1*7 = 13.

%e The second and third digits of Pi are 1 and 4; the corresponding digits in e are 7 and 1; so a(2) = 1*7 + 4*1 = 11.

%t nn=80;#[[1]]*#[[2]]+#[[3]]*#[[4]]&/@Partition[Riffle[RealDigits[ Pi,10,nn][[1]],RealDigits[E,10,nn][[1]]],4,2] (* _Harvey P. Dale_, Jun 13 2011 *)

%Y Cf. A000796 (Pi), A001113 (e).

%K nonn,base,less

%O 1,1

%A Don Love (moptop35(AT)hotmail.com), May 02 2009

%E Corrected and extended by _Harvey P. Dale_, Jun 13 2011