A223657Number of 7Xn 0..1 arrays with all rows having a nonnegative second derivative, and all and columns having a positive second derivative in a quadratic least squares fit, with one and two element arrays taken as having a zero second derivative.

60, 3600, 10425, 1059839, 24559913, 1119629805, 47882329200, 2061491256869, 95329202955957, 6980023496929171, 335311367775542739, 17119067750905601475, 1054799368422675063804, 74856492204365399292957

The first term appear at position 127.

…14808651328230664709384460955058223172535940812848…
position 127
termsstringfirst positionoccurrences
16012710,002,175
260360034,5481,001
360360010425not within 1,000,000,0000

Searched the first 1,000,000,000 digits. Strings longer than 12 digits are not indexed.